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SERVICE INFORMATION 

ON THE 

HAMMOND CHORD ORGAN 

(Models S, S-1, and S-4) 



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HAMMOND ORGAN 



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HAMMOND ORGAN COMPANY 

4200 WEST DIVERSEY AVENUE ' CHICAGO 39 ILLINOIS 



G.M. 7-65 



PRINTED IN U.S.A. 



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CONTENTS 

Page 

^§^ Figure 1 - Front View •.. 4 

General Description • 5 

Installation and Maintenance .«.. 5 

Special Equipment 5 

Musical Terms 5 

Notes and Octaves i 5 

Figure 2 - Arrangement of Keys in an Octave 5 

Tone Qualities 6 

Melody and Acconnpaniment 6 

Attack, Decay, Sustain, and Accent 6 

Vibrato 6 

How the Chord Organ is Played 6 

Turning On and Off 7 

Musical Divisions ••• 7 

Figure 3 - Chord Buttons 7 

Expression Control and Balancers 8 

Control Tablets 8 

How the Chord Organ Works 9 

Figure 4 - Simplified Block Diagram 9 

Description of Electrical Circuits 10 

Keyboard 10 

Vibrato 10 

Solo Oscillator 10 

Solo Frequency Dividers 11 

Solo Register Controls and "Solo Woodwinds" 11 

Solo Tone Controls ...., 11 

Solo Control Tubes 11 

"Organ" Oscillators 12 

XDrgan" Controls 12 

Chord Oscillators 12 

Figure 5 - Complete Block Diagram 13 

Figures 6, 6A, 6B, oC - Schematic Circuit Diagrams Separate Sheets 

Figures 7, 7A, 7B - Wiring Diagrams Separate Sheets 

Chord Buttons 14 

Mute 14 

Chord Control Tube and Chord Bar 14 

Sustain Cancel" 14 

Figure 8 - Chord Button Chart 15 

P re amplif ie r . » 1 ^ 

Bass Pedals 16 

Pedal Frequency Dividers 16 

Pedal Control Tube 16 

"Volume Soft" 16 

Expression Control Unit .••..••.•• 17 

Power Output Stage « 17 

Power Supply ^ 17 

Description of Components 17 

Generator Assembly 17 

Organ Oscillator Assembly 17 

Keyboard Chassis 17 

Keyboa r d • • • 17 



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Page 



Description of Components ••• 17 

Generator Assembly 1^ 

Organ Oscillator Assennbly 17 

Keyboard Chassis 17 

Keyboa r d 1 ' 

Figure 9 - Back View 18 

Figure 10 - Generator, Tuner, and Control Exposed 19 

Figure 11 - Keyboard, Chord Switch, and Balancers Exposed 19 

Figures 12, 12B - Generator 20, 20A 

Figures 13, 13A - Inside of Generator *. 53 

Figures 13B, 13C -Inside of Generator 55 

Figure 1 3D - Inside of Generator 57 

Figures 14, 14A - Wiring of Control Assembly 59 

Figure 15 - Organ Oscillator Assembly 21 

Figures 16, 16B - Inside of Organ Oscillator Assembly 21A, 22 

Figure 17 - Underside of Keyboard 23 

Chord Switch • 2 3 

Control Assembly • •• 23 

Tune r A s sembly • • • 23 

Expression Control and Power Switch 23 

Pedals and Pedal Switch 23 

Power Pack 2 3 

Figure 18 - Chord Switch 24 

Figure 19 - Pedal Switch - 25 

Figure 20 - Power Pack 25 

Se r vie e Ope r a tion s 2 6 

1. Tubes and Other Electrical Connponents 26 

2. Busbar Shifters 26 

3. Contacts on Control Tablets • 26 

4. Adjustment of Solo Tuning 26 

5. Tuning of Individual Organ and Chord Notes 2 7 

6. Tuning of Individiial Solo Notes 27 

Specific Service Suggestions 28 

7. Entire Instrument Fails to Play 28 

8. Vibrato Effect Completely Missing 28 

9. Radio Frequency Oscillation • 28 

Specific Service Suggestions for Solo Division 28 

10. All Solo Notes Fail or Are Weak 28 

11. Solo and Organ Divisions Fail or are Weak 28 

12. One Key Will Not Play a Solo Note 29 

13. One Key Plays Lowest "F" Solo Note 29 

14. One Solo Timbre Control Will Not Turn Off 29 

15. All Solo Notes Fail for One Position of "Solo Woodwinds" 29 

16. Solo Key Thumps or Clicks 29 

17. One Solo Register Control Does Not Play 29 

18. Solo "Bass" Does Not Play at All 29 

19. Solo "Bass" Does Not Play and "Tenor" Does Not Play with 

"Solo Woodwinds" off 29 

20. Solo "Bass" and "Tenor" Will Not Play at All 29 



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FIGURE I - FRONT VIEW OF CHORD ORGAN 



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Models S, S-1, and S-4 are almost exactly alike in appearance and nnusical 
operation. 

Model S uses octal tubes and one 12 inch speaker. The first units used type 
6SC7 frequency divider tubes which were later replaced with type 6SN7 tubes. 

Model S-1 has miniature tubes and one 12 inch speaker, and has some component 
values different from Model S. 

Model S-4 has miniature tubes and two 10 inch speakers. It differs in a number 
of circuit details from Models S and S-1, and has slightly different woodwork. 

Information in this book applies to all naodels unless otherwise stated. Where 
necessary, several circuit diagrams or other figures are supplied; for instance, figures An 
6, 6A, 6B, and 6C are schematic diagrams for various models. Where figure 6 is ^ 

mentioned in the text, it will be understood that it refers to all of these figures. 

Note that figures 1, 9, 10, and 11 are views of a typical Model S instrument, and 
other models differ in various details. 



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GENERAL DESCRIPTION 

The Hammond Chord Organ is completely self-contained (see figure l). It 
has a 37-note keyboard played with the right hand; a set of 96 chord buttons play- 
ed with the left hand; a chord bar operated by the palm or thumb of the left hand 
to accent chord rhythms; two bass pedals played with the left foot; twenty stop 
tablets for controlling the character of tones produced; three balancers for ad- 
justing the volume of the various divisions; and a knee-operated expression control 
to regulate the volume of the entire instrument. 

INSTA1.1.ATION AND MAINTENANCE 

wHivif° install the Chord Organ it is necessary only to attach the music rack, 
which IS packed with the console, and to plug the line cord into a wall outlet. 
The power source must be alternating current of the approximate voltage and 
frequency indicated on the name plate. The frequency need not be constant, but 
must remain within the indicated range. Oiling is not required. 

SPECIAL EQUIPMENT 

The ^'Owner's Service Suggestions" booklet gives fuU instructions for connec- 
ting a radio, phonograph, microphone, extension speaker, or ear phones to the 
Chord Organ . 

MUSICAL TERMS 

The service man who has had no musical training will find the following in- 
formation helpful in studying the operation of the instrument. 

Notes and Octaves 



Keyboard instruments are divided into "octaves" of 12 keys or notes, each 
with 7 '^aturals'^ (white keys) and 5 "sharps" or 'Ylats" (black keys) in a definite 
sequence. The pitch or frequency increases smoothly from left to right on the 
keyboard, and each note has a frequency twice that of the corresponding note in 
the next lower octave. Figure 2 shows the appearance of a typical octave of keys. 
The octave shown starts with C, but an octave may start with any key. 



K\ 



C# D# 

fOR\ fOH 



F# G# A# 




ONE OCTAVE 

FIGURE 2 -ARRANGEMENT OF PLAYING KEYS IN AN OCTAVE 



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Black keys occur in groups of two and^three in each octave and offer a con- 
venient way to identify the notes of the octave. Technically there is no difference 
between a black key and a white one, since each key has a frequency 6 percent 
greater than the frequency of the next one below it. The musical interval between 
any two adjacent keys is called a semitone. Each white key is called by a letter 
from A to G. A black key may be called a "sharp" of the note below it or a "flat" 
of the note above it; for instance, the black key between C and D may be called 
C# (C sharp) or Db (D flat). 

Tone Qiialities 

Any musical note has a definite fundamental pitch or frequency and also a 
certain "tone quality" or "timbre" depending on its wave shape. A simple flute- 
like tone contains only a single frequency. A complex tone includes not only the 
fundamental frequency but also one or nnore ^liarmonics" or "overtones", which 
are multiples of the fundamental frequency. The ear does not distinguish the 
harnnonics independently, but instead identifies the note as a connplex tone having 
the pitch of the fundanmental. 

In the Chord Organ the tone qualities of the various divisions nmay be changed 
by such controls as 'Mute", "Strings", Tlutes", "Solo Woodwinds", and the five 
"Solo Timbre" tablets. 



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Melody and Acconnpaniment 

Music requires not only a melody (one note played at a time) but also an ac- 
companiment consisting of additional notes which are in harmony with the melody. 
A group of notes which blend harmoniously when played together is called a chord. 

Attack, D ecay, Sustain, and Accent 

"Attack" describes the promptness with which a note soxinds after a key is 
pressed, and "decay" describes the rate at which it fades away. "Sustain" refers 
to the effect of a chord sounding softly while the chord bar is not held down. An 
"accent" is the effect by which a solo note is made to stand out from the accompan- 
iment; for instance, a note may be accented by giving it a percussive attack, like 
that of a banjo string being plucked. 

Vibrato 



The vibrato effect is created by a periodic raising and lowering of pitch at a 
rate of about six times a second. It is comparable to the effect produced when a 
violinist "wiggles" his finger back and forth on a string while playing, varying the 
pitch but maintaining constant loudness. 

In the Chord Organ the vibrato effect is available on all tonal divisions. On 
the solo division the extent of vibrato is adjustable. The terms "small" and 'Wide" 
refer to the extent of pitch variation. 



HOW THE CHORD ORGAN IS PLAYED 



This instrument is remarkably easy for anyone to play, and the service man 
will find it worth while to study the playing controls. A knowledge of how the in- 
strument is played will be found very helpful in locating the source of any trouble 
that may occur. 



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Turning On and Off 

To turn on, swing the expression control lever (see figure 1) downward and to 
the right. A pilot light above the keyboard indicates when the instrument is on. 
The volume increases as the lever is plpshed farther to the right. To turn off, 
swing the lever to the left and upward until the switch clicks. 

Musical Divisions 

The "Solo" Division is played by the keyboard and is used for playing a melody 
with the right hand. It is used practically all of the time as it has the greatest 
variety of tonalities in all pitch registers. As its name innplies, this division plays 
only one note at a time. If several keys are held down at once, the solo note of only 
the highest one will play. 

The "Organ" Division is independent of the solo division but is played by the 
sanne keys. Its tones augment those of the solo division and also make it possible 
to play full chords with the right hand. 

It is often desirable to use both the solo and organ divisions at the same time. 
As the melody note is usually the highest one played, it will be the one played by 
the solo division and can be emphasized by using a contrasting tone quality and 
greater volume on the solo division. 

The Chord Division has 96 Chord Buttons , played with the left hand, which 
furnish accompaniment to harmonize with the melody (see figure 3). As each 
button selects a full chord (along with the acconnpanying bass note), only one button 
is played at a time. The chord division also includes the Chord Bar , which is 
played with the palm or thumb of the left hand to sound the chord selected by the 
chord buttons, (if the "Sustain Cancel" tablet is off, the chord sotinds softly but is 
made louder by pressing the chord bar.) 

The Pedal Division has two bass pedals which are played with the left foot to 
so\ind the deep bass notes selected by the chord buttons. The two pedals play two 
different notes for each chord in order to give tonal variety. 



Db 

1 



At 

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MAJOR +6TH. 



NINTH- 



Eb 

1 
O 

o 



MAJOR- 
MINOR- 



SEVENTH- 



o 
o 
o 



DIMINISHED- 



AUGMENTED - 
MINOR 7TH — 



O 
O 
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6 
9 

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FIGURE 3 -CHORD BUTTONS, SHOWING BUTTON CAPS IN POSITION 
FOR LOCATING CHORDS IN KEY OF C 



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Expression Control and Balancers 

The Expression Control is the lever which extends from underneath the key- 
board. It is operated by the right knee, and serves to regulate the voliame of the 
entire instrument as well as to turn it on and off. 

The three Balancers are used to adjust the volume of tone produced by the 
'^pedal", "organ", and "solo" divisions. The best balance is generally obtained when 
the wording on all the knobs is horizontal. 

Control Tablets 

The twenty control tablets or "stop" tablets control the pitch range, tone quality^ 
attack, decay, and vibrato of the various divisions, as well as the overall volume 
and the effect of the chord bar. They are turned "on" to give the indicated effect by 
pushing them in at the bottom so that the dot is visible. 

' Volume Soft" . This tablet supplements the action of the expression control by 
reducing the volume of the entire instrument, and may be used to obtain soft music 
of great beauty. It may also be used to advantage when playing in a small room or 
when practicing, as it reduces the volume while maintaining the full range of the 
expression control. 

The Accompaniment Controls - "Sustain Cancel", 'TVTute", '*Pedal Fast Decay". 
"Sustain Cancel" removes the relatively soft tonal background which is produced 
when only a chord button is pressed. It is arranged to cancel the sustained back- 
ground rather than to add it because the background is usually desired. Regardless 
of the position of this control, pressing the chord bar causes the chord to sound at 
its full volume. 

'Mute" makes the chord button tones more mellow. 

"Pedal Fast Decay" is used to obtain a nnore percussive pedal tone. When it 
is used, the bass tone fades away very rapidly whenever a pedal is released. 

The "Organ" Tone Quality Selectors - "Strings" and 'Flutes". These two tab- 
lets control the tone quality of the "organ" division, which is played from the key- 
board. When neither is used, the "organ" division will be silent. The "Strings" 
tablet produces a very brilliant tone, the 'Flutes" tablet supplies a very mellow 
and pure tone, and both together give a full rich quality. 

The 'Vibrato Cancel" Controls . The word "cancel" is used in the name of these 
controls because they remove the vibrato effect when they are pushed in at the 
bottom. They are arranged to cancel the vibrato effect rather than to add it be- 
cause the vibrato is usually desired. 

"Organ and Chords", when pressed in at the bottom, cancels the vibrato of the 
chords as well as the "organ" division. 

With both "Solo Small" and "Solo Wide" pressed in at the bottom, the vibrato 
effect in the solo division is cancelled. To get a small solo vibrato, -press only 
"Solo Small" in at the top, and for a medium solo vibrato, press only "Solo Wide" 
in at the top. With both pressed in at the top, the nnaximum vibrato effect is 
heard on the solo division. 

The Solo Register Controls -^Bass", "Tenor", '"Soprano". These control the 
pitch range of the solo division. "Bass" places all the solo tones in a low register j 
"Tenor" moves them one octave higher; and "Soprano" moves them up an additional 
octave. These controls may be used in combination to produce a chorus of tones 
in octave relations similar to the effect obtained with organ couplers. At least 
one of these controls must be used in order to obtain a solo tone. 

The Tone Familv Selector - '*So1q Woodwinds". This tablet changes the quality 
of the solo tones from the string or brass family to the clarinet or woodwind fam- 
ily. The particular tone qualities within these two groups are determined by the 
solo tinmbre controls used. 

"Solo Fast Attack" and 'Solo Accent" . When neither control is used, the tonal 
attack of the solo division is very smooth and is well-suited for playing slow moving 
melodies such as ballads. When "Solo Fast Attack" is used, the attack beconaes 
very prompt and is useful for fast nnoving melodies. When "Solo Accent" is used 

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the attack is so rapid as to appear percussive, and accents may be produced by 
releasing one note before playing the next one. 

The Solo Timbre Controls -"Deep Tone". Tull Tone", "First Voice", "Second 
Voice", and "Brilliant". These five tone controls alter the frequency characteristic 
of the solo division to modify the quality of the tones selected by the Solo Register 
controls. "Deep Tone" emphasizes the low frequencies to provide a pure mellow 
type of tone, while "Full Tone" leaves the frequency characteristic essentially 
flat and gives a generally useful bright quality. 'First Voice" puts a resonance in 
the 750 cycle zone and "Second Voice" puts a resonance near 1000 cycles, producing 
beautiful solo voices of the horn type. 'Brilliant" emphasizes the higher frequencies 
and gives a piercing quality. These controls can be used singly or in various com- 
bmations to produce a great variety of effects. At least one of the five timbre con- 
trols must be used in order to obtain a solo tone. 

HOW THE CHORD ORGAN WORKS 

All tones of the instrument are generated by vacuum tube oscillators and are 
mixed and amplified by additional vacuum tube circuits. Figure 4 is a simplified 
block diagram of the entire instrviment. 

As figure 4 indicates, the playing keys control the ^*solo"and "organ" tone 
generating systems. Tones from either or both systems may sound, depending 
on the setting of the corresponding control tablets, and the relative volume levels 
may be regulated with the balancer knobs. 

Accompaniment tones originate in the chord generating system and are sel- 
ected with the chord buttons. The chords selected are sounded by pressing the 
chord bar, while the pedals play the correct bass notes to harmonize- with the chords. 
The functions of the chord button system and the pedal system are separately con- 
trolled by various control tablets. There is no balancer for the chord system, but 
the relative pedal voliime is regulated by a pedal balancer. 

Tones of all the divisions are combined at the amplifier and are regulated in 
volume by the expression control before being reproduced by the loud speaker. 



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21 

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or o 
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SOLO 
GENERATING 

SYSTEM 



ORGAN 

GENERATING 

SYSTEM 



KEYBOARD 




SOLO 
CONTROLS 



ORGAN 
CONTROLS 



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CHORD 
GENERATING 

SYSTEM 



CHORD 
BUTTONS 



CHORD 
CONTROLS 



PEDALS 



PEDAL 
CONTROLS 




AMPLIFIER 



SPEAKER 



EXPRESSION 
CONTROL 




FIGURE 4 -SIMPLIFIED BLOCK DIAGRAM 



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DESCRIPTION OF ELECTRICAL CIRCUITS 

When studying this section refer to the complete block diagram, figure 5, in 
which the parts are connected by arrows showing the signal paths. Controlling 
circuits are indicated by lines without arrows. The schenaatic circuit diagram, 
figure 6 (pages 39-41 -43-45), shows all circuits in detail. It will be found helpful 
also to refer to the wiring diagram, figure 7 (pages 47-49-51), which shows cables 
and other connections between parts of the instrument. 

Keyboard 

Four sets of contact springs are operated by the playing keys; tuning contacts 
and control contacts for the "Solo" division, plus tuning contacts and control contacts 
for the "organ" division. These four rows of springs make contact with four bus- 
bars extending the length of the keyboard. Some keys use four contacts and some 
use only three, as shown in figure 6. The tuning contact of each division always 
closes, tuning to the desired note, before the control contact of that division closes 
and causes the note to sound. 

The busbars are movable a short distance endwise, and a slotted stud under the 
keyboard can be turned to provide a fresh contact surface in case a particle of dust 
prevents a contact from closing. Refer to the section on "Service Operations" for 
use of this busbar shifter. 

Vibrato 



A single low frequency oscillator provides the vibrato effect for the entire 
instrument. It is composed of a triode tube in a phase shift circuit (see left end 
of figure 6), giving a frequency of about 6 cycles per second. The vibrato switch 
tube has a square wave output and its plate circuit acts as a switch to connect 
and disconnect small condensers across the solo oscillator t\ined circuit. The 
two solo vibrato switches provide compensating condensers in the 'Vibrato cancel" 
position in order to maintain the correct mean frequency with the vibrato on or off. 

The organ and chord divisions receive their vibrato from the vibrato switch 
tube cathode circuit as described later. When the effect is not desired, this ca- 
thode is grounded by the "Organ and Chords" vibrato cancel tablet. 



Jill 

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Solo Oscillator 

Each solo tuning contact tunes the single solo oscillator to the pitch of the 
"soprano" note associated with that key. When the lowest key is played (it has no 
solo tuning contact), all 37 solo tuning coils are connected in series to form the 
tuning inductance of the oscillator. When any other key is pressed, its tuning con- 
tact shorts out some of these coils (making less total inductance) and thus tunes 
the oscillator to the higher pitch associated with that note. If two keys are de- 
pressed at the same tinne, the solo oscillator will sound the pitch of only the higher 
one. The oscillator frequencies extend from 349 to 2793 cycles per second. 

The solo oscillator itself is a two-triode circuit with the tuned circuit con- 
nected to the first grid. The "Big Steps" and "Snnall Steps" tuning switches (upper 
left corner of figure 6) tune the entire solo division as a unit by placing small con- 
densers across the tuned circuit. Several small trimmer condensers are wired 
in parallel with the main tuning condenser (left end of figure 6) to bring the total 
tuning capacitance to the required value. 

An "oscillator rectifier" tube following the oscillator serves to furnish waves 
having a steep wave front suitable for operating the first frequency divider. 



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Solo Frequency Dividers 

There are two frequency divider stages, each including three triodes. One 
acts as a driver and pulse rectifier, supplying sharp and narrow negative pulses 
to actuate a symmetrical feed-back tripping circuit comprising two triodes. Either 
one (but only one) of these two triodes can be conducting at a time, for by drawing 
plate current it holds the other in a cut-off condition. 

Suppose, for example, that the first triode is conducting and the second is cut 
off. Now a negative input pulse impressed on the grids of both triodes will not 
affect the second one, which is already cut off, but will cut off the first. This prod- 
uces a positive pulse at the plate of the first triode, which is applied to the grid of 
the second triode through its feedback connection. The second triode then sud- 
denly conducts current, producing a negative pulse at its plate. This negative pulse, 
applied to the first triode grid through its feedback connection, insures that the 
first triode remains cut off. The situation is now exactly reversed, with the first 
triode cut off and the second conducting. 

The next input pulse will act on the second triode, cutting it off again and mak- 
ing the first conductive; and thus two input cycles are required to produce one out- 
put cycle. Each frequency divider circuit therefore divides its input frequency^n 
half producing an output signal one octave lower than the preceding divider. One 
triode plate of each divider stage furnishes a signal of rectangular wave shape to 
the following driver tube, and output signals are taken from the driver and divider 
plates . 

Solo Register Controls and "Solo Woodwinds " 

Signals for the "Soprano" register are taken fronn the master oscillator and the 
oscillator rectifier; those for the "Tenor" register from the first frequency divider 
and the driver following it; and those for the "Bass" register from the second fre- 
quency divider and a 'tass rectifier "'following it. The two signals to each register 
control are of the same frequency but different wave shape; and after passing through 
suitable tone filter circuits the two sets of signals furnish tones of the woodwinds 
family if the "Solo Woodwinds" tablet is on, or of the string family if this tablet is 
off. 

Solo Tone Controls 

After preliminary amplification by half of tube V8, the solo signal reaches the 
five tone controls, which are in series across the signal line. When "Deep Tone" is 
on (that is, the switch open), the signal develops across a condenser which empha- 
sizes the low frequencies; "Full Tone" has only a resistor, which leaves the fre- 
quency response essentially flat; "First Voice" and "Second Voice" are resonant cir- 
cuits which peak near 750 and 1000 cycles, respectively; and for "Brilliant" the sig- 
nal appears across an inductance, emphasizing the higher frequencies. 

Each of these tone control tablets (with the exception of "Brilliant") has a second 
contact connected in a volume compensating circuit to avoid excessive increase in vol 
\ime when two or more controls are used at once. 

Solo Control Tubes 

The solo input transformer Tl drives two control (or keying) tubes in push- 
pull. These are pentodes and are normally cut off because their grid circuit is at 
ground potential while their cathodes are held at about + 65 volts by a voltage divider 
^runH?th"' ""'u' '''^- ":?' ^^^^ Whenever a key is pressed its soL contro! contact 
grounds ^^i^sX^J^^Mc'^r'^"' removing the cut-off bias and causing the note to sound. 

When both the "Solo Fast Attack" and "Solo Accent" tablets are off, condenser C58 
makes the attack comparatively slow because a sudden decrease in the positive cat- 
hode voltage (caused by pressing a key) causes a negative surge through the condenser, 

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charges C60 negatively, and moves the grid voltage temporarily in the negative dir- 
ection. This maintains the cut-off condition for an instant after the key is pressed, 
until the charge in C60 leaks off through R77. 

Operating the "Solo Fast Attack" control eliminates this effect by disconnecting 
C58. 

When the "Solo Accent" control is on, it not only disconnects the slow attack con- 
denser but also connects a large condenser across R80. For a sudden decrease in 
cathode voltage (caused by pressing a key) this condenser effectively short-circuits 
the resistor and reduces the bias for an instant, causing the note to be loud at first 
and give a percussive effect. 

The signal fronn the control tube plates passes through the solo balancer to the 

preamplifier tube. 

"Organ" Oscillators 

Each of these 16 oscillators uses a single triode and a tapped coil. Most 
of them are used for two adjacent notes each, and some at the high and low ends of 
the keyboard play three adjacent notes. It happens that adjacent notes are almost 
never desired to be played together, and this arrangement enables only 16 oscil- 
lators to supply the 37 organ notes for the keyboard. The frequencies of these notes 
range from 175 to 1396 cycles. 

In each case the highest note is produced by a tizning condenser connected 
permanently across the entire tuning coil, and so the highest note of each oscil- 
lator requires no tuning contact. The oscillator does not operate, however, unless 
a key is pressed, for the control contact of each key supplies plate voltage to its 
oscillator. 

For the lower note of each oscillator, the tuning contact connects a second 
condenser across the lower part of the tuning coil. The coil tap is so located that 
this condenser may have the same capacity as the one permanently connected across 
the coil. 

In the case of an oscillator serving three notes, the nniddle tuning contact 
connects a third condenser in series with the one connected to the tap. This third 
condenser has a small resistor in series so that all three condensers may be of 
equal capacity. 

Each coil may be tuned by sliding half of the iron core toward or away from 
the other half, as described under "Tuning". 

" Organ^' Controls 

Two types of tone are supplied by each oscillator and selected by the "Strings" 
and "Flutes" tablets. The string signal connes from the lower end of the tuning coils 
of all the oscillators, with a resistor R185 to grovuid, while the flute signal co'mes 
through a decoupling resistor from the upper end of each tuning coil. 

The vibrato effect on the organ oscillators is obtained by applying a varying 
bias voltage (which comes from the vibrato switch tube cathode) to the grid resistor 
of each oscillator tube. This varies the frequency of all oscillators by a small amount 
during each vibrato cycle. To remove the vibrato effect, the "Organ and Chords" 
vibrato cancel tablet gro\xnds this grid return circuit. 

The combined organ signal goes through the organ balancer to the preamplifier 
tube. 

Chord Oscillators 



The six chord oscillators are similar to the organ oscillators, but cover the 
octave of frequencies from 175 cycles (F) to 330 cycles (E). Each one uses a single 
triode with a tapped coil, and each can play either of two adjacent notes, using two 

12 



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13 



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tuning condensers of the same capacity. The vibrato effect is produced in the sanne 
way as for the organ oscillators. It is possible to make the 12 chord notes available 
with only six oscillators, because no chord button uses more than five oscillators and 
no button requires two adjacent notes. 

Unlike the organ oscillators, these oscillators operate continuously, whether 
notes are being played or not. The signal output is taken from the plate circuit of 
each oscillator. ^ . ; . : 

Chord Buttons 

Each of the 96 chord buttons selects the correct three or four notes for that 
chord, as well as correct notes for the right and left pedals to play with that chord. 
(The notes selected for the pedals are the correct musical notes but are two octaves 
too high in pitch. They are lowered to the correct pedal pitch by the pedal frequency 
dividers described later.) 

The notes played by the buttons are predetermined by the positions of small 
projections on 96 pivoted levers underneath the buttons. These projections press 
actuators to operate the required contact springs. Each of the 96 buttons operates 
a different combination of contacts. Figure 8 shows the chord and pedal notes 
associated with each button. 

For each chord note a chord signal contact must close (carrying the oscillator 
signal) and a tuning contact must tune the corresponding oscillator if it is not already 
playing the correct note. (Remember that each of these oscillators operates con- 
tinuously at the higher of its two frequencies except when the tuning contact shifts 
it to the lower frequency.) Thus each button closes three or four chord signal con- 
tacts, as many as four tuning contacts, and also two additional contacts to select notes 
for the left and right pedals. 

The 24 contact springs include six chord signal contacts (one from each oscillator), 
six tuning contacts (each of which tunes one oscillator to the lower one of its two 
notes), six left pedal signal contacts, and six right pedal signal contacts. They nnake 
contact with four busbars. The tuning busbar is grounded; the chord signal busbar 
carries the chord signal to the chord control tube; and the last two busbars carry 
the pedal signals to the pedals. 

The busbars are movable a short distance endwise, and a stud extending from 
the bottom of the chord switch nnay be moved to the right or left to provide a fresh 
contact surface in case a particle of dust prevents a contact from closing. Refer 
to the section on "Service Operations" for use of this busbar shifter. 

"Mute" 

The chord signal, collected by the signal busbar of the chord switch, goes to the 
grid of the chord control tube. When the "Mute" control is on, it nnakes the tone more 
naellow by shunting a condenser across this signal line. In the off position (Models S 
and S-1 only) it short-circuits a resistor to maintain the signal level constant. 



Chord Bar and "Sustain Cancel" 



1'^' 



The chord control tube in Models S and S-1 is normally cut off by a negative 
voltage applied to its grid circuit. Pressing the chord bar substantially removes this 
voltage by connecting a resistor to ground, and the chord signal is then allowed to 
^pass to the amplifier tube (half of V20). Part of the chord signal ahead of the chord 
control tube is normally routed through the "Sustain Cancel" control to the preamplifier 
tube. THi^ rruakes the chord tones sound faintly when the chord bar is not pressed, and 
the chord bar then serves to accent the chord tones by making them louder. If the 
"Sustain Cancel" control is pushed in at the bottom this circuit is not connected, and 
the chord tones sound only w Ken the chord bar is pressed. Model S-4 has no chord 
control tube, and the chord bar switches the signal directly into the preamplifier tube. 
The "Sustain Cancel" control, in series with a resistor, is shunted across the chord 
bar contacts. Its operation is the same as descriBed above. 

14 



Button Notes in Chord 



Left 

Pedal 

Note 



Right 
Pedal 
Note 



Db6 

Db9 

Dbmj 

Dbm 

Db7 

Db- 

Db4- 



F 

F 

F 

G# 

F 

G 

F 



Dbm 7 G# 



G# A#C# 
G# ,B D# 
G# C# 
C# E 
G# B 
A# C# 
A C# 
B C# 



E 



Ab6 

Ab9 

Abmj 

Abm 

Ab7 

Ab- 

Ab+ 

Abm 7 



F G# 
F# A# 
G# C 
G# B 
F# G# 
F G# 
G# C 
F#G# 



C 
C 

D# 

D# 

C 

B 

E 

B 



D# 
D# 



D# 
D 

D# 



C# 
C# 
C# 
C# 
C# 
C# 
C# 

c# 

G# 
G# 
G# 
G# 
G# 
G# 
G# 
G# 



Eb6 


G A# C D# 


D# 


Eb9 


F G A# C# 


D# 


Ebmj 


G A* D# 


D# 


Ebm 


F# A# D# 


D# 


Eb7 


G A# C# Dilf 


D# 


Eb- 


F#A C D# 


D# 


Eb+ 


G B D# 


D# 


Ebm7 


F# A# C# D# 


D# 


Bb6 


F G A# D 


A# 


Bb9 


F G# C D 


A# 


Bbmj 


F A# D 


A# 


Bbm 


F A#C# 


A# 


Bb7 


F G# A# D 


A# 


Bb- 


G A# C# E 


A# 


Bbf 


F#A# D 


A# 


Bbm 7 


F G#A#C# 


A# 



G# 

G# 

G# 

G# 

G# 

G 

A 

G# 

D# 

D# 

D# 

D# 

D# 

D 

£ 

D# 

A# 

A# 

A# 

A# 

A# 

A 

B 

A# 

F 

F 

F 

F 

F 

E 

F# 

F 



F6 


F 


A C D 


F 


C 


F9 


G 


A C D# 


F 


C 


Fmj 


F 


A C 


F 


c 


Fm 


F 


G# C 


F 


c 


F7 


F 


A C D# 


F 


c 


F- 


F 


G# B D 


F 


B 


F + 


F 


A C# 


F 


c# 


Fm7 


F 


G# C D# 


F 


c 


C6 


G 


ACE 


C 


G 


C9 


G 


A# D E 


C 


G 


Gmj 


G 


C E 


C 


G 


Cm 


G 


C D# 


C 


G 


C7 


G 


A# C E 


C 


G 


C- 


F#A C D# 


C 


F# 


C + 


G# C E 


C 


G# 


Cm7 


G 


A# C D# 


C 


G 

Figure 



Button Notes in Chord 



Left 

Pedal 

Note 



Right 
Pedal 
Note 



G6 


G B D E 


G9 


F A B D 


Gmj 


G B D 


Gm 


G A#D 


G7 


F G B D 


G- 


G A#C#E 


G+ 


G B D# 


Gm7 


F G A# D 


D6 


F#A B D 


D9 


F#A C E 


Dmj 


F#A D 


Dm 


FAD 


D7 


F#A C D 


D- 


F G# B D 


D+ 


F# A#D 


Dm7 


F A C D 


A6 


F#A C# E 


A9 


G B C# E 


Amj 


A C# E 


Ana 


ACE 


A7 


G A C# E 


A- 


F#A C D# 


A+ 


F A C# 


Am 7 


G A C E 


E6 


G# B C# E 


E9 


F# G# B D 


Emj 


G# B E 


Em 


G B E 


E7 


G# B D E 


E- 


G A# C# E 


E + 


G# C E 


Em 7 


G B D E 


B6 


F# G# B D# 


B9 


F#A C# D# 


Bmj 


F# B D# 


Bm 


F# B D 


B7 


F#A B D# 


B- 


F G# B D 


B + 


G B D# 


Bm7 


F# A B D 


F#6 


F# A# C# D# 


F#9 


G# A# C# E 


F#mj 


F# A#C# 


F#m 


F#A C# 


F#7 


F# A#C# E 


F#- 


F#A C D# 


F#+ 


F# A# D 


F#m7 


F#A C#E 



G 
G 
G 
G 
G 
G 
G 
G 

D 
D 
D 
D 
D 
D 
D 
D 

A 
A 
A 
A 
A 
A 
A 
A 

E 
E 
E 
E 
E 
E 
E 
E 

B 
B 
B 
B 
B 
B 
B 
B 

F# 
F# 
F# 
F# 
F# 
F# 
F# 
F# 



D 

D 

D 

D 

D 

G# 

D# 

D 

A 
A 

A 

A 

A 

G# 

A# 

A 

E 

E 

E 

E 

E 

D# 

F 

E 

B 

B 

B 

B 

B 

A# 

C 

B 

F# 

F# 

F# 

F# 

F# 

F 

G 

F# 

C# 
C# 

C# 
C# 

c# 
c 

D 
C# 



Figure 8 -- Chord Button Chart 



15 



f^l 



Bass Pedals 

As pointed out above, each chord button selects the two proper musical notes 
for the two bass pedals. The note selected for the left pedal is always the "root" 
(or key note) of the chord, while the one for the right pedal is a musical '^ifth". 
In the case of the C major chord, for example, having notes C-E-G, the "root" note 
IS C and the "fifth" note is G (see chord button chart, figure 8). 

The pedal notes selected by the chord buttons cannot sound until one or the 
other of the bass pedals is played. As a pedal is pressed its signal contact closes 
first, carrying the corresponding note from the chord switch busbar to the pedal 
frequency dividers. The pedal note is not heard, however, until the pedal control 
contact closes, energizing the pedal control tube. This tube follows the pedal fre- 
quency dividers and will be discussed later. 

The signal contacts of the two pedals are mechanically interlocked so that the 
last-played contact always remains closed until the other pedal is pressed. This 
insures that the correct pedal note will continue to be available for the duration 
of the pedal decay tinne. 

Pedal Frequency Di viders 

The pedal notes selected by the chord buttons and pedals are the correct notes 
of the scale but are still in the pitch range of the chord tones. To bring them to 
the right pitch for the pedals they are fed into two frequency dividers, substantially 
identical to the solo frequency dividers. Each one divides its input frequency in 
half, which means that its output is the same note of the scale but an octave lower. 
Thus the two dividers in cascade lower the signal two octaves below the chord notes, 
producing pedal notes in the frequency range of 44 to 82 cycles. 

A limiter tube preceding the pedal first divider establishes waves of suitable 
shape to trip the divider properly. Signals from the limiter, the first divider, and 
the second divider are mixed to give the desired pedal tone. The combined pedal 
signal IS then fed through a tone filter network into the pedal control tube. 

Pedal Control Tube 

+. .. ^"^ Models S and S-1 this tube is normally cut off by a negative voltage applied 
to Its grid circuit. When the pedal keying wire is grounded by^pressinVa Pedal it 

by K.: by and C220. When the pedal is released, the tube is cut off aeain as the 

cL7ef ti'T^'' ^i^" «"^ ^^^' "^"^S" ^"^- ^ *1^^ "P^dal Fast Decay" swx"chTs 
closed the tube cuts off nnuch more rapidly because the resistance in'Ehis leak path 
is greatly reduced, allowing the condenser to charge sooner. 

In Model S-4 this circuit is essentially the same except that the pedal control 
tube is normally cut off by a positive voltage applied to its cathode circuit. The note 
sounds when the pedal keying contact connects the grid circuit to the same positive 
potential . 

The signal from the plate of the pedal control tube goes through the pedal bal- 
ancer to the amplifier tube V20, where it joins the combined solo, organ, and chord 
signals. 

"Volume Soft " 

This control shunts a resistor across the signal line to reduce the volume of 
the solo, organ, and chord tones equally. It is arranged to reduce the volume of 
the pedal tones by a smaller amount in order to compensate for the frequency re- 
sponse characteristic of the human ear. 



16 



Expression Control Unit 

After passing through a stage of amplification, the signal reaches the expression 
control unit, a special variable air condenser with two sets of fixed plates and a 
set of movable plates coupled to the knee-operated expression control lever. With 
the lever in 'loud" position the plate signal of V20 goes directly to V27, while in the 
"soft" position it goes through a tone -compensated attenuating network. 

Power Output Stage 

Tube V27 is a common-cathode -innpedance phase inverter, which drives the 
two output tubes. An adjustable feed-back condenser C237 serves as a factory vof- 
ume adjustment. 

Power Supply 

The power supply circuit is conventional in design, using resistance-capacity 
filters. 

DESCRIPTION OF COMPONENTS 

Most of the assemblies comprising the instrument are visible in figures 9, 
10, and 11. 

Generator Assembly 

The generator contains the solo oscillator, frequency dividers and tuning 
switches; the vibrato oscillator and vibrato switch tube; the six chord oscillators; 
the pedal frequency dividers; the expression control unit; all the control tubes 
and amplifier tubes; and portions of the power supply. 

This chassis is pivoted between the keyboard chassis blocks (figure 9). By 
removing two screws (see figure 9) it can be unfastened so that it will swing down 
(as shown in figure 10) to expose the components inside the chassis. The instrument 
can be operated (but the expression control will not work) with the generator in 
this position. 

Figure 12, showing the outside of the chassis, identifies all external components, 
and figure 13 (pages 53-55-57) is a view of the inside, with all components identified 
by the schematic diagram reference symbols. 

Organ Oscillator Assennbly 

This chassis contains circuits of the 16 "organ" oscillators. Figure 15 iden- 
tifies the external components and figure 16 shows the inside. 

If it is necessary to work on the inside of this chassis, it will be found con- 
venient to place it on a chair directly behind the instrument. The cables are long 
enough to reach to this position. 

Keyboard Chassis 

This unit includes the two keyboard chassis blocks and the units mounted on 
them; the keyboard, chord switch, control assennbly, tuner assembly, and generator. 

Keyboard 

The keyboard itself includes 37 molded plastic keys and a contact mechanism 
sealed against dust. Figure 17 shows the locations of busbar shifters for the key- 
board and the chord switch. 

17 



SCREWS HOLD 
TOP COVER 



GENERATOR 
ASSEMBLY 



BRACKETS 

HOLD 
GENERATOR 




ORGAN 
OSCILLATOR 
ASSEMBLY 



FIGURE 9 - BACK VIEW 



I 



18 



» 



CONTROL ASSEMBLY 
(COVER removed) 




SOLO MAIN TUNING CONDENSER 



TUNER ASSEMBLY 



GENERATOR IN HORIZONTAL 
POSITION 



FIGURE 10- GENERATOR , TUNER ASSEMBLY, AND CONTROL ASSEMBLY EXPOSED 




CHORD SWITCH 



FIGURE II - KEYBOARD, CHORD SWITCH, AND BALANCERS EXPOSED 



19 



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ill 



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t/) — t- qcq: 




O ^ lOuJu 




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EACH TUBE FUNCTIONS 
AS AN OSCILLATOR FOR 
THE TWO COILS AT 






LO 

r* 

LO 

c 

MID 
f* 

MID 
A* 

MID 
D 

HI 
F* 

HI 

A^ 

HI 
D 




-Q*-A-A* 
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'organ'tuner 
.coils for 
lowest octave 

OF KEYS 








L 41 


LO 
A 


L 4^ 














RiaHT OF IT 


f V 13 J I2AU7 
(v\AJ I2AU7 
( VI5 JI2AU7 
f V 16 Jl2AU7 
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L 43 


LO 
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-A-A* 
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ntt- F 


'organ"tuner 
i coils for 
middle octave 

OF KEYS 


L45 


MID 


L46 




















L 47 

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MID 

C 


L48 




















L49 


MID 
E 


L50 
















-F-F* ^ 

-6,-G* 

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-B-C 

-C*-D 
-D*-E-F 


ORGAN"TUNER 
ICOILS-FOR 
HIGHEST OCTAVE 
OF KEYS 








■ 
L 51 


HI 


L 52. 




















L53 


HI 

C 


L54 




















L5S 


HI 
E 
4 


L56 






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note: model s uses type 

MODELS S-l AND 5-^ 
AS SHOWN 

Fl 


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\ USE TYPE 12AU7 

GURE 15 -0 


RGAN 


V COILS ARE TUNE.D T 
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BUSBAR SHIFTER FOR 
CHORD BUTTONS 



FRONT RAIL SCREW 
AND CLIP 



2 KEYBOARD END BLOCK 
MQUNJTIMG SCREWS 



BUSBAR SHIFTER 
FOR KEYBOARD 




^ 

o o hJ 



£. 



FRONT RAIL 




KEYBOARD TERMINAL STRIP COVER 



2 KEYBOARD CHASSIS 
MOUNTING BOLTS 



8 SCREWS FASTEN 
TERMINAL STRIP COVER 
TO KEYBOARD 




FIGURE 17 - UNDERSIDE OF KEYBOARD 



Chord Switch 

The chord switch assembly includes the chord buttons, the mechanism under 
them, the chord contacts and busbars, and some electrical components associated 
with them. Figure 18 shows the locations of connponents, the positions of contacts, 
and some details of the mechanical construction. 

Control Assembly 

This unit includes all the control tablets and their contacts, the tone control 
networks, the register control circuits, the balancers, and the pilot light. Figure 
14 (page 59) shows the position of components in this assembly. 

Tuner Assembly 

This is a long channel in which all the solo tuning coils are naounted. It also 
includes the main solo timing condenser and the solo tuning trinamer condensers. 

Expression Control and Power Switch 

The knee -operated expression control lever is attached to the wood case of 
the instr\iment, and the power switch is attached to it. The back end of the lever 
pushes the expression control unit (mounted on the generator) when the generator 
is in its normal position. 

Pedals and Pedal Switch 



The two bass pedals are attached to the underside of the wood case, and 
bakelite strips extending through the case bottom operate contact springs in the 
pedal switch. Figure 19 shows details of the pedal switch. 



Power Pack 



The power pack includes only the power transformer, the rectifier tube, and 
one resistor. Figure 20 shows its internal connections. 



23 




13 B^ AND S-lJgK GN(S-4)- 



YEL OR 



GKI IKCS an d SH) 



BN IK(S-4) 



FOUR 5CREW5 
A,B,C-* D FASTEN 
CHORD SWITCH" 
TO KEYBOARD 



CHORD CONTACT^ 
KIUMBERS 

LEVERS WITHIN 
EACH GROUP ARE 
LOCATED AS 
SHOWN 50 THAT 
EACH BUTTON 
PRESSES ONE 
LEVER - 



UPPER __ 

COMB\ ll 



(S AND S-l) 




>6 TAPPED HOLES 

FOR COVER 

MOUNTING 



CODE NOTCHES 
INDICATE CORRECT 
LOCATIONS OF 
LEVER GROUPS 



-SCREWS CiD REACHED , TOP ^/ 1 E \Ay 

FROM UNDERSIDE OF CWHH BUTTONS AND COVER REMOVED) 
KEYBOARD. 



MODELS S AND S"! 



, WIRES TO CHORD 
- BAR CONTACT 



MODEL S-4 



LOWER_ 
COMB 



RETAINER PLATE- 
HOLDS 96 LEVER 
SPRINGS IN PLACE 
N0TE:THE RIGHT 
FOUR ROWS OF 
SPRINGS ARE 
DYPD RED. THE 
LEFT FOUR ROWS 
ARE NOT COLORED. 




-CHORD CONTACT 
NUMBERS 



-CONTACT SPRINGS 



RIGHT PEDAL 
SIGNAL BUSBAR 



-LEFT PEDAL 
SIGNAL BUSBAR 



BOTTOM VIEW 



FIGURE 18- CHORD BUTTON SWITCH 



24 



if . 



I 



LEFT PEDAL 
SIGNAL CONTACT 



RETURN SPRING- 



RIGHT PEDAL_ 
ACTUATOR 



RIGHT PEDAL 
CONTROL CONTACT 




right pedal 
"signal contact 



PIVOTED LATCHING 
MECHANISM 



left pedal 
"actuator 



LEFT PEDAL 
CONTROL contact 



FIGURE t9-PEDAL SWITCH 



POWER RECTIFIER TUBE VII 



POWER TRANSFORMER T3 




SWITCH 



O (2) (^ 

B- B+ 6.3 V 6 NO. 



LINE CORD BLACK RED i YELLOW BRQWIN GREEN BARE 




FIGURE 20 - POWER PACK 



25 



SERVICE OPERATIONS 

The first few numbered suggestions deal with general service problems 
that may be encountered, and later paragraphs give specific suggestions for certain 
troubles which may occur. 

1. Tubes and Other Elec trical Components 

As in other electronic devices, the vacuum tubes are among the most likely 
cause of unsatisfactory operation. The tubes are all standard radio types and can 
be tested in the customary way to see if they are dead or weak. However, such 
tubes occasionally show intermittent leaks which fail to show up on conventional tube 
testers, and therefore it is highly recomnnended that the service man rely on in — 
terchanging tubes wherever possible, rather than simply testing them. A suspected 
tube may generally be interchanged with another of the same type to see if the trouble 
appears in its new location. 

Most of the synnptoms of tube failure are indicated in following paragraphs. 
Note that many of the tubes are double triodes and in sonne cases a defective tube 
nnay cause trouble in more than one section of the instrument. 

Refer to the "Owner's Service Suggestions' booklet for a simplified non- 
technical procedure for checking the vacuunn tubes. 

Other circuit components, particularly resistors and condensers, may oc- 
casionally give trouble. The resistors are all standard sizes and can be secured 
through local sources. Their resistance values are shown on the circuit diagram. 
Most of the condensers are standard types and can be secured locally. Their ca- 
pacity values are shown on the circuit diagram, and replacements must have equal 
or higher voltage ratings. All that are special are listed at the end of this section 
so that they can be ordered irom the factory. Transformers and coils are also 
listed, as they are all special. 

Z . Busbar shifters 

If a key contact or chord switch contact appears to be failing (see following 
paragraphs for symptoms), adjust the corresponding busbar shifter as instructed 
under ;'C on tact Shifters" in the "Owner's Service Suggestions" booklet. The two shif- 
ters are visible in figure 17. 

3. Contacts on Control Tablets 

The control or stop tablets also have precious metal contacts, which are 
similarly subject to the possibility of failure because of dirt. If a contact appears 
to be failing, remove the control assembly cover as directed in the section on "Pro- 
cedure for Removing Parts." After locating the offending contact spring and the 
fixed contact it touches, clean them by wiping the contact surfaces gently, taking 
care not to place a permanent bend in the contact spring. The corner of a small 
piece of stiff paper is handy for this purpose. In severe cases it may be necessary 
to rub the contact surfaces gently with a piece of very fine sandpaper. (Never use 
emery cloth or enaery paper.) 

4. Adjustment of Solo Tuning 

The two tuning knobs on the back surface of the generator (figure 12) tune 
all solo notes up or down simultaneously. The procedure for adjusting them is 
described under "Simple Tuning" in the "Owner's Service Suggestions" booklet. 



Z6 






5. Tuning of Individual Organ and Chord Notes 

Complete instructions for such tuning are given under "Screwdriver Timing" 
1^ in the "Owner's Service Suggestions" booklet. 

6. Tuning of Individual Solo Notes 

The Chord Organ is carefully timed to standard pitch at the factory and can 
be expected to remain satisfactorily in tune for a long time. The solo tuning system 
is particularly stable in regard to the nnusical interval between notes, and so the 
"Owner's Service Suggestions" booklet does not mention this type of timing. However, 
after long use under extremely adverse humidity conditions, it is possible that some 
solo notes may not be exactly in tune with each other. Before concluding that re- 
tuning is necessary, be absolutely certain that the notes are actually far enough out 
of tune to make them unsatisfactory. Remember that small differences in tuning are 
actually desirable in many cases because they add a 'thorus" effect which gives added 
richness to the tone. A note generally requires retuning if the "Small Steps" knob 
must be turned more than one step to bring it in tune. 

If it is decided that tuning is required, the following procedure is recommen- 
ded. A Hammond Organ is preferred as a pitch standard because its pitch is posi- 
tively established by the frequency of the electric current supply. Never use any 
other instrument as a pitch standard unless it is known to be precisely tuned to 
standard pitch. 

Note: While any single chord or organ note of the 
Chord Organ can be tuned individually, no solo note 
can be adjusted witkout affecting the ones below it. 
If any solo note has to be retuned, it will be necessary 
^ to follow this entire procedure in order. 

(a) Connect the voice coil terminals of the Chord Organ to one set of plates (either 
horizontal or vertical) of an oscilloscope, and connect the voice coil terminals 
of a Hammond Organ to the other set of oscilloscope plates. Pull out only the 
first white drawbar (fundamental) of the organ and press the corresponding pre- 
set key. If the organ is equipped with vibrato, tremulant, or chorus, they should 
be turned off. 

(b) Leave the Chord Organ on for at least 15 minutes before starting to tune. Press 
all 20 control tablets in at the top and then press "Tenor", "Full Tone", and the 
three ^Vibrato Cancels" in at the bottom. 

(c) Remove the, top cover of the Chord Organ, exposing the solo tuning coils. The 
generator and control assembly cover must be in their normal positions. 

(d) Observe the setting of coil 37 (figure 7 shows the locations of all coils). The end 
of the coil bobbin should be within l/32" of the end of the iron core. If it is not, 
loosen the clannping screw, slide the coil carefully forward or backward until the 
bobbin end is even with the core, and tighten the- screw. 

(e)Hold down the highest key (F) of the Chord Organ and the highest F key of the 
Hammond Organ. Adjust the volume levels so that the oscilloscope has approxi- 
nnately equal horizontal and vertical deflections. 

(£) Adjust the "Big Steps" and "Small Steps" solo tuning knobs to make the oscilloscope 
1^ wave pattern move as slowly as possible. 



27 



(g) Adjust coil 37, if necessary, to bring it in tune with the Hanrimond Organ as in- 
dicated by the oscilloscope pattern standing still or naoving no more than one 
cycle in two seconds. 

(h) Release the F keys and hold down the next lower keys (E) on the two instruments. 
Adjust coil 36 in the same way. Repeat for all other keys and coils in chromatic 
order downward. It is important to start tuning with the highest note and progress 
down one key at a time, because the tuning of the lower notes is dependent upon 
all of the higher coils. 

(i) After tuning, recheck all notes to see that all coils are tuned accurately. 

SPECIFIC SERVICE SUGGESTIONS 

The Chord Organ appears complicated, but a careful study of the circuit diagram 
J (figure 6) shows that any possible trouble can generally be isolated by observing the 

I operation of the various controls. This technique is illustrated by the following list 

I of possible troubles, arranged according to their symptoms. It is assumed in all 

I cases that the entire instrument plays correctly with the exception of the symptoms 

|- mentioned. 

( Only the most likely causes of each symptom are listed, but similar symptoms 

I may be caused by other components directly associated with the circuits mentioned. 

When a trouble has been traced to a certain part of the instrument, the service 
man will find it helpful to observe voltages and compare them with those shown on 
the circuit diagram (figure 6). All D-C voltages are taken with a ZO,000-ohms-per- 
volt meter, and some may vary if a meter of different sensitivity is used. All are 
based on a line voltage of 117 volts. 

Wave shapes may be checked witn an oscillosciope in some parts of the circuit, 
particularly the oscillatbrs and frequency dividers, and compared with patterns shown 
on the circuit diagram (figure 6). It should be noted that some oscilloscopes will show 
the patterns inverted. 

7. Entire instrument fails to play. K all the tubes are lighted but no sound can 
be obtained, the rectifier tube VU may be defective. In this case all DC volt- 
ages will be missing. If voltages are present, probably there is a defect in 
the amplifier tube (half of VZO) or the phase inverter and driver tube V27. 

8. Vibrato effect completely missing. The vibrato oscillator (half of tube V2) 
naay not be working, or the vibrato switch tube (half of V5) may be defective. 

9. Radio Frequency oscillation. Check R254, which acts as a radio frequency 
suppressor. This resistor was not used in early Model S instruments, and 
should be added if RF oscillation occurs. 



rt 



10. 



SPECIFIC SERVICE SUGGESTIONS FOR SOLO DIVISION 

All solo notes fail to pla y or are weak . One of the solo oscillator tubes 
^J^^^^^I^TlHJTSTn^rV^TJFTre .„lo preamplifier tube (half'^o'f V8) 



I may be defective 



11. 



Solo and organ divisions fail to play or are weak. The preamplifier tube (half |,^> a 

oi v^u; IS probably defective. In Model S or S-1 with defective preamplifier C { 

chords play when chord bar is pressed, but do not sustain or are weak when 
Sustain Cancel' is off; in Model S-4, all solo, organ, and chord tones are absent 
or weak, whether "Sustain Cancel" is on or off. 



28 



1 



12, Onejtey will not play a solo note on any reg ister control. A dirty solo control 
contact on one key may make the note play irregularly or fail entirely. Adjust 
the keyboard busbar shifter (paragraph 2). 

^^- Q^e key plays lowest "F " solo note instead of its correct pitch ( with adjacent Itpv^ 
playing correctly;. In this case the solo tuning contact i s dirty. This may also 
make the note noisy or irregular. Adjust the keyboard busbar shifter (paragraph 2). 

^'*' One solo timbre contro l will not turn off. The tablet has a dirty contact. Clean 
as directed in paragraph 3. 



15. 



16, 



All solo notes fail to play for one position of the "Solo Woodwinds" tab let. One 
of the contacts on the tablet is dirty. Clean as instructed in paragraph 3. 

Solo key thumps or clicks. An annoying thump each time a key is released indi- 
cates that the two solo control tubes V9 and VIO are not properly matched. In 
this case install two new tubes of the same make. 



^^- One solo register control does not play for one position of the "Solo Woodwinds" 
tablet, In this case one contact of the register control tablet is probably dirty 

}f^l ^l instructed in paragraph 3. K the "Bass" tablet fails with "Solo Woodwinds" 
off, the bass rectifier tube (half of V7) may be defective. 

^^' Solo '^ass" does not pl ay at all (with "Solo Woodwinds" either on or o ff) Divider 
tube V6 may be at fault. This may also make the tones irregularly noisy or an 
octave too high in pitch. a j j 

19- ^°^° ''^!!^" .1°^^ """^ P^^y ^^ ^^^ ^"^^ "Tenor" does not play with "Solo W oodwinds" 
tablet off. The second divider driver tube (half of V5) may be defective. This 
may also make the tones irregularly noisy or an octave too high in pitch. 

^°- Sol" "Bass" a nd "Tenor" will not play at all (with "Solo Woodwinds" tablet in either 
^osingnl. I^ivider tube V4 or its driUr tube (half of V3) may be defective! This 
may also make the tones irregularly noisy or an octave too high in pitch. 

^^- Solo "Bass 'I and "Tenor" will not play at all and "Soprano" will not play with "Solo 
Wood^ nds" tablet off . The oscillator rectifier tube (half of Vi) may be defectiv e. 

Note: There is a common bias resistor R37 for all solo and pedal dividers, 
bypassed by C31. and a fault in one of these parts may cause all solo 
and pedal dividers to fail. It is possible also that a fault in one di- 
vider may upset this common bias and make all dividers fail. A help- 
ful procedure in this case is to shunt a resistor across R37 of what- 
ever size IS necessary to restore the bias to its normal value. 
All dividers should then work with the exception of the faulty one. 

^^- Solo small vibrato or solo wide vibrat o does not come on when corres ponding 

•Vib rato Cancel tablet is pushed in at top. The tablet mav h:.^^ :. ak^L _ 

tact. Clean as instructed in paragraph 3, 

^^' Average pitc h o f s olo note changes when "Solo Small" or "Solo Wi de" is turned 
on and off. This means that the compensating contact on the tablet is dirty, 
t/lean as instructed in paragraph 3. 



29 



24. 



25. 



f ' 



26. 



SPECIFIC SERVICE SUGGESTIONS FOR ORGAN DIVISION 

One key will not play an organ note . A dirty organ control contact on one key 
may make the note play irregularly or fail entirely. Adjust the keyboard bus- 
bar shifter (paragraph 2). 

Two, three, four, five, or six adjacent keys will not play organ notes. Each organ 
oscillator tube is a double triode, and each half of each tube plays two or three 
adjacent notes. If one triode fails, two or three notes will fail to sound, and if the 
whole tube fails it will make four, five, or six notes inoperative. 



Missing Notes 

low F, F#, & G; or low G#, A, & A#; or all 6 
low B, C, & C#; or low D, D# &: E; or all 6 
middle F & F#; or middle G & G#; or all 4 
middle A & A#; or middle B & C; or all 4 
middle C# & D; or middle D# & E; or all 4 
high F & F#; or high G & G#; or all 4 
high A & A#; or high B t C; or all 4 
high C# & D; or high D#, E^ & F; or all 5 



Tube which may 
be faulty 

V12 

V13 

V14 

V15 

V16 
V17 
V18 

V19 



"Organ Strings" or "Organ Flutes"will not play for any key. The defective tab- 
let probably has a dirty contact. Clean as instructed in paragraph 3. 

27. One key plays organ note having pitch of next higher note or second note higher. 
In this case the organ tuning contact is probably dirty. This may also make 

the note noisy or irregular. Adjust the keyboard busbar shifter (paragraph 2). 

28. Organ and chord vibrato effect will not turn off. The "Organ and Chords" vib- 
rato cancel tablet has a dirty contact. Clean as instructed in paragraph 3. 

SPECIFIC SERVICE SUGGESTIONS 
FOR CHORD BUTTON AND PEDAL DIVISIONS 
Trouble in the chord section of the instrument, which includes the chord button 
and pedal divisions, is likely to affect both of these divisions. It is most likely to be 
observed in the pedals, however, because any single note in a chord tends to be 
masked by the other notes. 

29. One pedal fails to play with any chords. If the other pedal plays correctly, the 
oscillators, pedal control tube, and frequency dividers must be working. The 
signal contact or control contact in the pedal*^ switch is probably dirty and can 
be cleaned in the same manner as the control tablet contacts (paragraph 3). 
See figure 19 for positions of contacts. 

30. Both pedals fail to play with any chords. The pedal control tube (half of V8) 
nnay be defective, or the trouble may lie in the pedal frequency divider system 
(half of V7 plus V24, V25, and V26). Failure of the divider systenn may also 
make the pedals irregularly noisy or may make them an octave or two octaves 
too high in pitch. See note after paragraph 21. 

31. One pedal fails to play with certain chords. If the other pedal plays correctly 
with all chords, all the oscillators must be working. This means that one ped- 
al signal contact in the chord switch is failing. Adjust the chord switch busbar 
shifter (paragraph 2). 



30 



1 



Faulty 


Tube which may 


oscillator 


be faulty 


F-F# 


V21 


G-G# 


V21 


A-A# 


V22 


B-C 


V22 


C#-D 


V23 


D#-E 


V23 



1^ ^L ^^' One pedal fails to play with some chords and the other pedal fails to play with 

^ ^^ some other chords. Probably one or more oscillators are inoperative. As 

the left pedal plays the "root" note of the chord, the buttons with which the left 
pedal fails to play will indicate which oscillator is defective. If half a tube is 
faulty, both notes associated with that half will be missing. If the entire tube 
is defective, four notes will be absent. 

* ■ 

I Lreft pedal fails 

[ to play with 

all F & F# buttons 
all G & Ab buttons 
all A & Bb buttons 
all B & C buttons 
all Db & D buttons 
all Eb & E buttons 

If an oscillator is not operating, its two notes will be missing from the right 
pedal as well as the left. Refer to the chord button chart (figure 8) for the ex- 
act notes each pedal plays with'each chord. The same notes will also be miss- 
ing from the chords, but their absence may not be readily noticeable. 

^^- Pitch of one pedal is one note too high on some chords. This will happen if a 
tuning contact in the chord switch fails to close. If failure of a tuning contact 
^ ^^ makes a note play the wrong pitch, this note will have the wrong pitch wher- 

ever it occurs on either pedal pr in the chords. (See chord chart, figure 8). 
Adjust the chord switch busbar shifter (paragraph 2). 

^^- "Pedal Fast Decay" tablet does not affect the decay rate. Probably the contact 
is dirty. Clean as instructed in paragraph 3. 

35. Chord bar has no effect (but chords will play if "Sustain Cancel" tablet is pressed 
in at the to pj . The chord bar may have a dirty contact; if so, the contact may be 
reached by removing the chord bar (held in place by two screws) and may be 
cleaned in the same manner as the control tablet contacts (paragraph 3). If the 
instrument is Model S or S-1, the chord control tube (half of VI) may be defective. 

J 

^ 36. One note missing from a chord. It is difficult for anyone who is not a trained 

musician to identity a missing note by listening to the chord alone. A chord may, 
however, be checked against the corresponding organ notes. 

To do this, turn off all control tablets (by pushing them in at the top) except 
'Tlutes", "Strings", and "Organ and Chords" vibrato cancel. Refer to the chord 
button chart (figure 8) to see which notes are supposed to be present in the chord, 
and play these same notes in the lowest octave of keys on the keyboard. By alter- 
nately playing the keys and the chord button, it is easy to tell if the two chords 
sound alike. 

• K this test indicates that a note is missing, but the pedals play correct- 

ly on all buttons, the most likely cause is a dirty chord signal contact 
in the chord switch. This will cause the two notes of one oscillator (see 
chart in paragraph 32) to be naissing fronn all chords where they are used. 
Adjust the chord switch busbar shifter (paragraph 2), 



31 



r 



ELECTRICAL PARTS LIST 



This list includes only the parts which have special or unusual values so that 
replacements must be ordered from the factory. All other electrical components 
can generally be secured locally. If it is fo\ind necessary to order any parts not 
listed here, they may be identified by their reference symbols shown on the sche- 
matic wiring diagram. To be sure of getting the correct parts always mention the 
model and serial number of the instrument. 



REFERENCE 
SYMBOL 



CAPACITY 
MFD. 



REPLACEMENT 
VOLTAGE TYPE PART NUMBER 



C31 

C67 

C68 

C69 

C65 

C66 

C87,C89,C90,C93 

C95,C96,C177,C179 

C181,C183,C185,C187 

C99,C101,C102,C105 

C107,C108,C189,C191 

C193,C195.C197,C199 

C111,C112,C116 
C117,C121,C122 

C126,C127,C131 
C132,C136.C137 

C141,C142,C146 
C147,C151,C152 
C156,C157.C161 
C162,C166,C168,C169 

C237 



4 
30 
20 
20 
30 
30 

.167 * 
.141 * 

.0882 * 
.0556 * 

.035 * 



100 

400 

400 

400 

450 

450 

200 
200 

200 
200 

200 



Electrolytic AO-26386-0 



Electrolytic AO-26385-0 



Plastic Film AO-500-32 



Plastic Film AO-500-35 



Plastic Film AO-500-43 



Plastic Film AO-500-51 



Plastic Film AO-500-59 



.000028-. 000090 



Variable 



AO-21468-0 



* s^erc^tL^t'lctorr'Th'^t"*^ ''fi!^" F'^"" "^^ approximate, and exact values are 
t^e^S-tTa'r^.^^^^^^^^^^^^ — ^^sso^Lj^^^ 



32 



RESISTORS 



REFERENCE 
SYMBOL 


OHMS 
8000 


TYPE 
Variable 


REPLACEMENT 
PART NUMBER 


R85 


AO-20293-30 


R90 


30 


10 watt wirewound 


AO-19124-3 


RlOO 


16,000 


10 watt wirewound 


AO-19124-108 


Rise 


25, 000 


Variable 


AO-20293-31 


R265 


1 meg. 


Variable 


AO-20293-32 



TRANSFORMERS 



REFERENCE 
SYMBOL 



FUNCTION 



REPLACEMENT 
PART NUMBER 



T3 

Tl 
T2 

T4 



Power (117V 60 cycles) 

Solo input 
Solo output 

Output 



AO-26334-1 (S) 
AO-26577-1 (S-1) 
AO-26577-4 (S-4) 

AO-26361-0 

AO-26363-0 (S.S-l) 
AO-26363-1 (S-4) 

AO-20936-1 (S,S-1) 
AO-20936-2 (S-4) 



33 



PROCEDURE FOR REMOVING PARTS IN NEED OF REPAIR OR 

REPLACEMENT 
To Replace Pilot Lamp 

(a) Unscrew white dome cover and replace bulb with a #44 (bayonet base). 
To Remove a Control Tablet 

(a) If console has a back panel, remove by taking out 12 screws. 

(b) Rennove outermost screw from bracket fastened to each end of generator 
and swing generator into horizontal position. 

(c) Remove console top by taking out screw from underside of cleat at each ' 
end of console. 

(d) Loosen four screws at ends of tuner assennbly (figure 10), slide tuner as- 
sembly back, lift off and carefully rest it upside down on generator. 

(e) Remove six screws in top and loosen six screws in back of control assem- 
bly cover (figure 10) and lift off. To avoid scratching woodwork, slip a piece 
of cardboard in at each end'of console. 

(f) Rennove two screws at each end in base of control assennbly and prop up so 
that ends of tablet assemblies are accessible. 

(g) Ten tablets are pivoted on each of two long rods. Using cutting pliers, pull 
out rod which holds tablet to be removed, pulling it out only far enough to 
replace faulty tablet. In case rod does not extend far enough to hold 

it with pliers, tap other rod (at far end of assembly) gently to drive desired 
rod out a small amount. 

(h) Carefully hold tablets in alignment when sliding rod back. 

(i) If more than one tablet is removed, be sure to replace all tablets in their 
original positions. 

To Remove a Balancer Potentiometer 

(a) If console has a back panel, remove by taking out 12 screws. 

(b) Remove outermost screw from bracket fastened to each end of generator 
and swing generator into horizontal position. 

(c) Remove console top by taking out screw from underside of cleat at each 
end of console. 

(d) Loosen four screws in tuner assembly (figure 10), slide tuner assembly 
back, lift off and carefully rest it upside down on generator. 

(e) Remove two screws at each end in base of control assembly and carefully 
lay control assembly on generator. To avoid scratching woodwork, slip 

a piece of cardboard in at each end of console. 

(f) Pull off all three balancer knobs after turning them to their minimum position 
(counterclockwise) and marking position of wording to insure replacement 

in correct positions. 

34 



(g) Detach potentiometer bracket by removing three screws under knobs. 

(h) Unsolder wires from faulty potentiometer and remove it. Refer to wiring 
diagram (figure 7) when reconnecting wires. 

(i) Turn all potentiometers to their minimum position (counterclockwise) to 
insure replacement of knobs in correct positions. 

To Remove Chord Bar 

(a) Take out two screws next to the chord bar, lift the bar, and unsolder two 
wires frotn it. When reconnecting, be sure to connect wires to same 
terminals. 

To Rennove Chord Switch Cover and Buttons . 

(a) Remove chord bar as above. 

(b) Lay strips of scotch tape across all buttons so they will not fall out when 
cover is removed. 

(c) Take out remaining four screws in cover and lift out cover with buttons. 
To Remove Chord Switch 

(a) If console has a back panel, remove by taking out 12 screws. 

(b) Remove outermost screw from bracket fastened to each end of generator 
and swing generator down into horizontal position, 

(c) Remove console top by taking out screw from underside of cleat at each 
end of console. 

(d) Loosen four screws at ends of tuner assembly (figure 10), slide tuner assem- 
bly back, lift off and carefully rest it upside down on generator. 

(e) Remove two screws at each end in base of control assembly and carefully 
lay control assennbly on generator. To avoid scratching woodwork, slip a 
piece of cardboard in at each end of console. 

(f) Unsolder cable and wires frona ternninal strip at rear of chord switch. Refer 
to wiring diagram (figure 7) to reconnect cable and wires. 

(g) Remove four screws fastening chord switch to keyboard (figure 18) and lift 
out chord switch. 

(h) For access to coil springs, refer to figure 18. 

To Remove Generator Assembly 

(a) If console has a back panel, remove by taking out 12 screws. 

(b) Pull out speaker plug from generator chassis (Models S and S-l). 

(c) Remove outermost screw from bracket fastened to each end of generator, 
and swing generator into horizontal position. 



35 



(d) Remove console top by taking out screw from underside of cleat at each 
end of console 

(e) Unsolder all external wires from generator terminal strip. 

(f) Take out pivot screw at left end of generator, push generator to left to un- 
hook from other pivot, and lift out. 

To Remove a coil from Generator 

(a) Remove two screws from coil strap. 

(b) Carefully pull coil away from chassis an inch or two to permit unsoldering 
wires from three lugs on inner side of coil. Refer to figure 13 when recon- 
necting wires. 

To Remove On -Off Switch 

(a) K console has a back panel, remove by taking out 12 screws. 

(b) Rennove outermost screw from bracket fastened to each end of generator 
and swing generator down into horizontal position. 

(c) Remove two screws which screw into switch nnounting plate from underside 
of upper shelf. 

(d) Lift out entire switch assembly and expression control arm. 

(e) Remove switch by taking out two screws and unsoldering two wires. 
To Remove a Pla ying Key 

(a) If console has a back panel, remove by taking out IZ screws. 

(b) Pull out speaker plug from generator chassis (Models S and S-l). 

(c) Remove outernnost screw from bracket fastened to each end of generator 
and swing generator down into horizontal position. 

(d) Rennove console top by taking out screw from underside of cleat at each 
end of console. 

(e) Take out pivot screw at left end of generator, push generator to left to xrn- 
hook from other pivot, and lift and block up generator in vertical position 
as high as possible without damaging connecting cables. 

(f) Remove two screws at each end in base of control assembly. To avoid scratch- 
ing woodwork, slip a piece of cardboard in at each end of console. 

(g) To remove a black key loosen its key mounting screw at rear of keyboard, 
lift up control assembly, unhook key from screw and lift out key. 

(h) To remove a white key loosen its key mounting screw at rear of keyboard, 
and those of adjacent black keys. Lift up control assembly, unhook these 
keys from screws, push them back, and lift out white key. 



CM 



c»i 



36 



To Remove Keyboard 

(a) If console has a back panel, rennove by taking out 12 screws. 

(b) Pull out speaker plug from generator chassis (Models S and S-l). 

(c) Rennove outermost screw from bracket fastened to each end of generator 
and swing generator into horizontal position. 

(d) Remove console top by taking out screw from underside of cleat at each 
end of console. 

(e) Rennove keyboard terminal strip cover by taking out eight screws (figure 17). 

(f) Unsolder all wires from keyboard terminal strip. For S-4 form B only, 
unsolder solo tuner cable from, solo tuner assembly. Refer to wiring 
diagram (figure 7) when re soldering these wires, 

(g) Tilt generator enough to remove tuner cable clip from rear of keyboard 
and pull out cable (S, S-l, and S-4 form A). Loosen four screws holding 
tuner assembly (figure 10), slide tuner assembly back, and lift out. 

(h) Unsolder cable and wires fronn terminal strip at rear of chord switch. Refer 
to wiring diagram (figure 7) when reconnecting cable and wires. 

(i) Remove four screws fastening chord switch to keyboard (figure 18) and lift 
out chord switch. 

(j) Unsolder pedal switch cable wires from generator terminal strip. 

(k) Disconnect cable from power pack. 

(1) Take out pivot screw at left end of generator and push generator assembly 
to left to unhook from other pivot. 

(m) Remove two screws at each end in base of control assembly, carefully rest 
control assembly on generator, and lift out both assemblies. 

(n) Remove two brackets (to which control assembly and tuner assembly were 
attached) from keyboard chassis mounting blocks by taking out four screws. 

(o) Detach keyboard assembly fronn console by taking out four hexagonal bolts 
from keyboard chassis mounting blocks (two from underneath keyboard 
and two from underneath upper shelf). 

(p) Remove front rail screw and clip (figure 17) which fastens front rail to key- 
board. 

(q) Lift out keyboard assembly with chassis mounting blocks attached. 

To Remove Organ Oscillator Assembly 

(a) Remove three screws from lower shelf and three screws from bracket 
mounted on underside of upper shelf. To facilitate servicing, it will be 
found convenient to place the oscillator chassis on a chair directly behind 
the instrumient. The cables are long enough to reach to this position. 

37 



i i 



(b) If necessary to disconnect completely, remove keyboard terminal strip 
cover by taking out eight screws (figure 17). Unsolder orange wire and 
organ oscillator cable from keyboard terminal strip. Refer to wiring di- 
agram (figure 7) when resoldering these wires. 

To Rennove a coil from Organ Oscillator- Assembly 

(a) Remove two screws from coil strap. 

(b) Carefully pull coil away from chassis an inch or two to permit vinsoldering 
wires fromi three lugs on inner side of coil. Refer to figure 16 when recon- 
necting wires. 

To Remove Pedal Switch 



(a) If console has a back panel, remove by taking out 12 screws. 

(b) Remove back cover of pedal switch by taking out four screws. 

(c) Take out two screws fastening pedal switch to lower shelf and carefully 
lift out. 

(d) Unsolder wires. See wiring diagram (figure 7) when reconnecting wires. 
Refer to figure 19 for details of contact assemblies. 

(e) When replacing pedal switch, be sure to seat actuators (figure 19) into pedal 
slots carefully. 

To Remove a Pedal 

(a) If console has a back panel, remove by taking out 12 screws. 
if (b) Place suitable pad on floor and tip console over on side farthest from pedals. 

(c) From underside of pedal remove screw from center of pedal; also remove 
nut, washers and two felt spacers from end of pedal fastened to console. 

(d)L.ift off pedal carefully to avoid damaging bakelite actuators in pedal switch. 



4 



38 



I 




1 



BASS 
RECTIFIER 



SOLO REGISTER CONTROLS 




WOODWINDS 



SOLO 
PREAMPLIFIER 



lOA va 



SOLO TIMBRE CONTROLS 







16 ORGAM OSCILLATORS 



APPROPRIATE 
PRESSED TO h 
O^ ANY OflGA 





CHORD Slf^NAL 



PEDAL I5T FREQUENCY DIV-DER 



PEDAL 2ND FREQUENCY DIVIDER 



. .27 MEG ■"■' 




f*aJ^? 



ICONT 
O— 



ROU CONTACTS 



TERh4.4. TERM. 3 T£RM.3 TEAM. 2 TERM.[3t4 iTEBM.ZtS TEWM.4 TERM.5 TERM.l3t.4 ItEBM.2I,J 



~~pU^EG^ .2 



r 'T° 



PEDAL CONTROL i 



FIGURE 6-SCHEMATIC CIRCUIT DtAGRAM OF CHORD ORGAN 
MOOEU S (BELOW SERIAL NUMBER 3S00J 



I 



1 



SOLO 
PREAMPLIFIER 



SOLO TIMBRE CONTROLS 



SOLO CONTROL TUBES 




TERM.y ld..2.3 T.RM.4TeJ[5 ^ErJ^^ Jj^^ 



bf CHORD ORGAN 
NUMBER 3S00J 



m 



CONTROL TUBES 



POWER SUPPLY 




39 



5OL0 OSCILLATOR 




CHORD CO*. TACT NUMbERS 

TUNING BUSBAR 

CHORD SIGNAL BUSBAR 

LEFT PEDAL SIGNAL BUSBAR 

RIGHT PSOAL SIGNAL BUSBAR 



CHORD SWITCH 



mm^SSm-—'^ 



BASS 

CTIFIER 



SOLO REGISTER CONTROLS 



SOLO 
PREAMPLIFIER 



SOLO TIMBRE CONTROLS 





TESM.4 TERM. 3 TERM. 1 TERm.2 TERM,! 11,4 ItERM.StS TER>/..4 TERM.5 T£RM.Ill.A '"^"'^•^'■S 



PEDAL CONTROL C 



FIGURE 6A-SCHEMATIC CIRCUIT DIAGRAM OF CHORD ORGAN - MODEL S 

(revised to owit ftsc7 TU5es-5tRtAL Ha s&oo *ND above) 



r 



// 



6.3V HEATERS 



(generator and 

ORSAN oscillator) 



2E 3D SB 




POWER SUPPLY 



-nnmTTinnnn- 



5000 5600 3900 






MEANS WIRE ♦le IN GROUP f 





WIkE 


CODE LETTERS 


A WIRES 


CONNECT 


GENERATOR TO CONTROL ASSEMBLY 


B WIRES 


CONNECT 


GENERATOR TO CHORD SWITCH 


C W1HE5 


CONNECT 


GENERATOR TO KEVBOAHD 


WIRES 


CONNECT 


GENEHATOR TO SPEAKER 


e WIRES 


CONNECT 


GENERATOR TO POWER PACK 


G WIRES 


CONNECT 


GENERATOR TO PEDAL SWITCH 


U WIRES 


CONNECT 


CHORD SWITCH TO PEDAL SWITCH 


J WIRES 


CONNECT 


KEYBOARD TO CONTROL ASSEMBLY 


H WIRES 


CONNECT 


CHORD SWITCH TO CONTROL ASSEMBLY 


i. WIRES 


CONNECT 


KEYBOARD TO SOLO TUNER ASSEMBLY 


P WIRES 


CONNECr 


ORGAN OSCILLATOR A5SEM. TO POWER PACK 


R WIRES 


CONNECT 


ORGAN OSCILLATOR ASSEM. TO KEYBOARD 



NTROL TrtBLETS SHOWN IN OFF POSITION (PUSHED IN *T TOP) 
A TABLET IS ON WHEN DOT IS VISIBLE 
ALL VOLTAGES SHOWN ARE+FROM GROUND UNLESS OTHERWISE NOTED 

VOLTAGES WEASURED WITH 20,000 OHMS-PER-VOLT METER 
FOR TUBE LOCAIIONS SEE FIGURES 12,15.20 
FOR LOCATIONS 3F COMPONENTS SEE FIGURES 13,14,16.18 
FOR ROUTliK OF WIRES SEE FIGURE 7 



(aCRlAL NO. 9337 
TO 12000) 
RAOtO-P^ONO" 



POWER AMPLIFIER 



C237 



,O00024-.0O0090 



PHONO 

(iERlAL NO. iSOO 

TO 9336) 



41 



I 



SOLO OSCILLATOR 



OSCILLATOR 

RECTIFIER 



^^1^ 



U. 



SOLO 1ST FREQUENCY DIVIDER 



-^-r ^ i_r 




SOLO 2ND FREQUENCY DIVIDER 



BASS 
RECTIFIER 



J-r 



BRATO CANCELS - 




SOT--^^ fi=.51£TCRS 
SELECTED AT FACTORY 
TO ADJUST VIBRATO 
SPIED 



KEYBOARD 





0I3R 6t*= 




SOLO TUNIMS 
TRIMMER CONDENSERS « ±: o ^zt^o S:i:° 
(0,t,2 OR 3 USED) " " " 



, MAIN SOLO 
TUNINS 
>. CONDENSER 



SOME LATE 5-1 CONSOLES HAVt 
SERIES GRID Re SI5TORS RI9VA, 
R2 02A, R207A,R2I3 A,R2I7A,AWD 
R2 22A A 5 SHOVVM ON MODEL 
6-4 SCHEMATIC. 



PLATE WAVE FORM 
OF ALL CHORD 
OSCILLATORS 




CHORD CONTACT NUMBERS 

ING BUSBAR 

CHORD SIGNAL BUSBAR 

LEFT PEDAL SKaNAL BUSBAR 

RIGHT PEDAL SIGMAL BUSBAR 



CHORD SWITCH 



I 



LI-: 



-B 



I 



SOLO 

PREAMPLIFIER 



SOLO TIMBRE CONTROLS 




FIGURE 6B-SCHEMATIC CIRCUIT DIAGRAM OF CHORD ORGAN MODEL 5-| 



r 



SOLO CONTROL TUBES 



6BA6 2tOV 



POWER Supply 



dn^z^ 



'T- .00*(AT IMVERTtR TUBE V 27) 



6.3v heaters 
{generator and 

ORGAN oscillator) 



C67 



-^m f I fn m — o-^ 



C69 



MEANS WIRE I 







WIRE CnOE LETTERS 


A 


WIRES 


CONNECT GttvlERATOR To CONTROL ASSEMBLY 


8 


WIRES 


CONNECT StNERATOR TO CHORD SWITCH 


C 


WIRES 


CONNECT GtMERATOR TO KEYBOARD 


D 


WIRES 


CONNECT GENeRATOR TO SPEAKER 


£ 


WIRES 


CONNECT GiNERATOR TO POWER PACl^ 


G 


WIRES 


CONNECT Gi NERATOB TO PEDAL SWITCH 


H 


WIRES 


CONNECT CHORD SWITCH TO PEDAL SWITCH 


J 


WIRES 


CONNECT KEYBOARD TO CONTROL ASSEMBLY 


1^ 


WIRES 


CONNECT CHORD SWITCH TO CONTROL ASSEMBLY 


L 


WIRES 


CONNECT KiYBOARD TO SOLO TUNER ASSEMBLY 


P 


WIRES 


CONNECT ORGAN OSCILLATOR ASSEM. ^0 POWER PAi^K 


^ 


WIRES 


CONNECT O^SAK OSCILLATOR ASSEm. TO KEMBOARD 




ALL CCNTROu TABLETS ShO^N iN OF"^ POSITION (p\J$HlO 1-^ AT TOp) 

A TABLET IS ON WHEN CCT IS --illBLE 

ALL VOLTAGES SHOWN ARE+ FROM GROUND UNLESS OTHERWISE NOTED 

ALL VOLTAGES MEASURED WITH 20,000 OHMS-TER - VOuT METER 

FOR TUBE LOCATIONS SEE FIGURES I2,i5.20 

FOR LOCATIONS OF COWPONENTS SEE FIGURES 13,14,16,(8 

FOR ROUTING OF WiRfS SEE FIGURE 7 



43 




ir 



1 



SOLO 

PREAMPLIFIER 



SOLO^TIMBRE CONTROLS 




Lk L13 



_> V^ 




FIGUf=^E GC-SCHEMATiC CIRCUIT DIAGRAV OF CHORD ORGAN MODEL S-4 



¥S 



SOLO 

PREAMPLIFIER 



SOLO*'TlMBRE CONTROLS 



SOLO CONTROL TUBES 




TtJ^7 rr^>^. ^' TERM.7 TEBM.6 TERM.h77 [TERMJt. 



lA 



K' OF CHORD ORGAN KAODEL S-4 



y5 



CONTROL TUBES 




POWER SUPPLY 



PILOT LIGHT 

*44. 27A R69 



dn 



OM-OFF SWITCH Qt 
EXPRESSION CONTRCL I 
LEVER 



■T-.0047 Cat inverter tube vz?) 



IP 6.3V HEATERS 

(generator and 

^^ ORGAN oscillator) 




-SOLO TUNING BUSBAR 

— KEY NAMES 

— KEY NUMBERS 



-SOLO TUNER COILS 



cancelled) 



_ 4 MODEL S-4 FORM B, 
SG^O CONTROL BUSBAR 
IS SHOUNDED AND CONTACTS 
ARE CONNECTED TO WIRE K. 



VVMEN AMf PeOAL IS 
PRESSED THIS POI«T 
RISES TC *tV. 



A WIRES 
a WIRES 
C WIRES 
D WIRES 
E WIRES 
G WIRES 
H. WIRES 
J WIRES 
K WIRES 
L WIRES 
P WIRES 
R WIRES 



WIRE CODE LETTERS 
CONNECT GENERATOR TO CONTROL ASSEMBLY 
CONNECT GENERATOR TC CHORD SWITCH 
CONNECT GENERATOR TO KEYBOARD 
CONNECT GENERATOR TO SPEAKER 
CONNECT GENERATOR TO POWER PACK 
CONNECT GENERATOR TO PEDAL SWITCH 
CONNECT CHORD SWITCH TO PEDAL SWITCH 
CONNECT KEYBOARD TO CONTRCL ASSEMBLY 
CONNECT CHORD SWITCH TO CONTROL ASSEMBLY 
CONNt'CT KEYBOARD TO SOLO TUNER ASSEMBLY 
CONNE'JT ORGAN OSCJLLATOR ASSEV. TO POWER PACK 
CONNECT ORGAN OSCILLATOR ASSEM. TO KEYBOARO 



ALL CONTROL TABLETS SHOWN IN OFF POSITION (PUSHED IN AT TOp) 

A TABLET IS ON WHEN OCT 15 VISIBLE 

ALL VOLTAGES SHOWN ARE-*- FROM GROUND UNi.ES3 OTN€t<WISE-n<nED 

ALL VOLTAGES MEASURED WiTH 20,000 OH^IS-PER-VOLT METES 

FOR TUBE LOCATIONS SEE FISURES 12,(5, 20 

FOR LOCATIONS OF COMPONENTS SEE FIEUREJ IJ,i4,(6.ie 

fCR ROUTING OF WIRES SEE F'SURE T 



POWER AMPLIFIER 




45 



k- 



TUWIN6 COIL 
NUMBERS 



C81,C82,CB3 




SOLO TUNER 



3Q ^"^ 37 36 (9 18 35 36 17 16 35 34 17 16 33 34 15 16 33 32 15 14 31 32 (3 14 31 30 13 12 29 30 II i2 29 28 II fO 27 

L ^ L LL LL LL LL LL LL LL LL LL LL LLLL LL LL LL LL LL LL 



f^EYBOARD TERMINAL STRIP (RE, 



1? ^ ^^ ^r7 ^r^ ^^ ^"^ ^^ ^^ ^' ^^ ^r? ^8 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 II 10 9 8 7 6 5 4 3 2 I 4! 2C IC 
R RRRRRRRRRRRRRRRRRRRRRRR R R RRRrrrrr r R R R R r r 




-BROWN WIRE 2feA IS CONNECTED TO THIS 
TERMINAL INSTEAD OF TUBE. SOCKET 
IN MODEL S CONSOLES ONLY 



WIRE CODE LETTER5- 



1 2 21 5 4 

— E C A E E 

RED RED BNi 6V 6Y 



'O- 



ORGAN OSCILLATOR ASSEMBLY- (iNSiD£ view) 




oooooo 00 oooooooo oo OOOOOO 



o irz o o~ 



O O o o 



oooooooo 



\ \ .\\.\\\ W ^i l \\\\\\\[ i | ^ \\\ AW ^ 



37 
R 



35 34 33 32 31 30 29 2fl 27 26 25 24 23 22 21 20 t9 IS 17 16 15 14 J3 
.^^iL 5. A AA^.^R^_ R RRRRRRR RR RRRR 



12 10 9 7 

RRRR 



6 4 3 r 40 38 
R R R R R R 




FIGURE 7 - WIRING DiAGRAr 

CHORD ORGAN 
MODEL S^Sl 



r/ 



f 



SOLO TUNER AS5EMBLY-(?*£:aR vc*} 




;i 28 



1 " 




27 




[ h I 


1) c 


S I 


) c 



5 4 3 25 22 16 24 

-*E CAEEEAAA A 

RED RED SNi 6V 6Y BK BK GN BN G^4 

SH SH SH 



GN YEL OR i 



PEDAL SWITCH CABLE 




SPEAKER PLUG F 
INTO GENERATOR 
CHASSIS 



p cp o o o o o 



o o o o o 



TTT\ 



> 4 3 t 40 38 41 

t R R R R R R 



SPEAKER CABLE 



RW SIDE 

VIEW OF 

PLUG 





- COLOR CODE - 


WIRES BLACK UNLE5S 


0T>«RW»5E MARKED 


B 


BARE 


m 


BLACK 


&N 


BROWN 


RED 


RED 


OR 


ORANSe 


YEL 


YEUJOW 


94 


€REEN 


ei. 


e*-ue 


vio 


vioLrr 


6t 


GREY 


WH 


WHITE 


SH 


Sm ELDED 




PEDAL SWITCH 



WIRE CODE LETTERS 

WIRES CONNECT GENERATOR TO CONTROL A^EMBLY 

B WIRES CONNECT GENERATOR TO CHORD SWITCH 

C WRES CONNECT GENERATOR TO KEYBOARD 

WIRES CONNECT GENERATOR TO SPEAKER 

E W«ES CONNECT GENERATOR TO POWER PACK 

WIRES CONNECT GENERATOR TQ PEDAL SWITCH 

WRES CONNECT CHORD 5WITCH TO PEDAL 5WITCH 

WIRES CONNECT KEYBOARD TO CONTROL A5SEWVBLY 

WV^S CONNECT CHORD SWITCH TO CONTROL ASSEMBLY 

L WIRES CONNECT KEYBOARD TO 50L0 TUNER ASSEMBLY 

P WIRES CONNECT ORGAN OSCILLATOR A S5EM.TO POWER P*CK 

R WIRES CONNECT ORGAN OSCILLATOR A5SEM. TO KEYBOARD 



IRING DIAGRAM OF 
>RD ORGAN 



I 



47 



TUNING COIL 
NUMBERS 



C61,C«2.C83 



SOLO TUNE 



6 6 



'3 y 30 y 12 



38 37 

L L 



37 36 19 18 35 36 !7 18 35 34 17 16 33 34 15 16 33 32 (5 14 31 32 13 t4 31 30 13 12 29 30 II 12 29 28 II 10 

L LL LL LL LL LL LL LL LL LL LL LL LL LL LL LL LL LL L 



KEYBOARD TERMINAL STRIP ( 



40 3» 38 37 36 35 34 33 32 31 30 29 28 27 2£ IS 24 23 22 21 20 19 18 17 16 IS (4 (3 12 II 10 9 8 7 6 5 
RRRRRRRR RRRRRRRR R R RRRRRRRRRRRRRRrrr R 




9 o 6 9 o 9 



919 9 9 9 



00000000 



3 2 

R R 



9 9 9 9 99 9 



ORSAN OSCILLATOR CABLE 



^ 



CONTROL TABLETS OR STOP TABLETS (REAR view) 




WIRE CODE LETTER5- 



I 2 2 5 

-^ E f C E E 

RED RED bN 6Y 



ITCH VZ7 



ON-OFP 

5WI 



ORGAN OSCILLATOR ASSEMBLY- (iNSiOE view) 




000000 00 00000000 00 000000 



00 OOpOOOQ 



o o o o p o o o 



\ \ .\\\\\ vt-M\ \ WW WW \ \ft^ 



\ \ \ \ \r7~W-~\~\ \ \ \^ 



37 35 34 33 32 3» 30 29 28 27 26 25 24 23 22 21 20 19 16 17 16 IS 14 13 (2 tO 9 7 

RRRRRR^_R_R RRRRRRRR RR RRRR RRR R 



6 4 3 I 40 38 

R R R R R R 




FIGURE 7A-W I RINiG DIAGR. 

CHORD ORGAN 

MODEL 5-4 (FORM ) 



Aj 



— "^^-^ 



-1 

SOLO TUNER ASSEMBLY- (REAR view) 



n 



t9 I 



12 29 2S II 

L L L L 



10 27 28 9 

L L L L 



10 27 26 9 

L L L L 



8 25 26 7 

L L L L 



a 25 24 7 

L L L L 



6 23 24 5 

L L L L 



6 23 22 5 

L L L L 



4 21 
L L 



22 1 

L L 



4 2t 
L L 



20 3 

L L 



2 19 20 I 
L L L L 



ErminAL strip (pear view) 



3 2 

R R_ 



41 2C IC 2J U 



Q o o o o ? '^ P — ? y ? ? 



3« 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 ift 17 16 15 14 13 12 H 

LLLLLLULLLL L L L L L L L^ 

31 



lO 9 a 7 
L L L L 




TUNING COIL 
NUWeERS 



C8l,CS2,Ca3 



SOLO TUNER A 




KEYBOARD TERMINAL STRIP (ptAP 



37 36 35 34 33 32 31 
R R R R R R R 


^ 29 2S 27 26 25 24 23 22 2l 20 ig 18 17 I6 15 14 13 12 il lO 9 8 7 6; 
RRRRRRRPRRRRRRRRRRRRRR RRRl 


I99? ??????????? jl 9??? 9 999 9 999V9 9999 li 


1 11 M 1 1 J 1 1 1 1 1 11 1 


^■c-.„ : _ , J 





ORGAM OSCILLATOR CABLE 



CONTROL TABLETS OR STOP TABLETS (REar vew) 




I 2 2 5 4 3 

WIRE CODE LETTERS — • E C E E E E 

RED BED BN OY GY B 



ON -OFF 
SWITCH 



o- 



ORGAN OSCILLATOR ASSEMBLY-Onside view) 



39R46R 



000000 ^ll'^ OOP 00000 00 oocooooo 00 00000000 c 



Q 00 



p o o. o o c 



\ i o U U I U i \ \i iii\,l\ii l ir^-t U U I U k i l o o U U \ ^^F\ 



37 

R 



35 34 33 32 31 30 29 26 27 26 25 24 23 22 21 20 »9 18 17 16 »5 14 l3 12 lO 9 7 

R R R R R R R^Rf«„ RRRRRRRR RR RRRR RRR R 



HEATERS 




FIGURE 7B-W[RIKJG DIAGRAM 
CHORD ORGAN 
MODEL S-4 (form B) 

Si z 



ami^- 



SOLO TUNER ASSEMBLY -(rear View) 




2R 


o o 


o 


o o 


1 


'' " '^ 


D O 


o. 


o o 


o 1 








■~\ 


\ 


\ 


\ 


h h 


h 


6 o 


M 


3 1 

R R 


40 
R 


38 

R 


41 
R 




— COLOR COOE — 


WIRES 6LACK UNLESS 


OTHERWISE MARKED 


s 


BARE 


BK 


BLACK 


BN 


BROWN 


RED 


RED 


OR 


ORANGE 


VEL 


VEL LOW 


GN 


GREEN 


BL 


BLUE 


VIO 


VIOLtT 


GY 


GREY 


WH 


WHITE 


3H 


SHIELDED 




PEDAL SWITCH 



A WIRES 
B WIRES 



c 


WIRES 


D 


WIRES 


E 


WIRES 


G 


WIRES 


H 


WIRES 


J 


WIRES 


K 


WIRES 


L 


WIRES 


P 


WIRES 


R 


WIRES 



WIRE CODE LETTERS 

CONNECT GENERATOR TO CONTROL ASSEMBLY 

CONNECT GENERATOR TO CHORD SWITCH 

CONNECT GENERATOR TO KEYBCWRO 

CONNECT GENERATOR TO SPEAKER 

CONNECT GENERATOR TO POWER PACK 

CONNECT GENERATOR TQ pEOAL SWITCH 

CONNECT CHORD SWITCH TO PEDAL SWITCH 

CONNECT KEYBOARD TO CONTROL ASSEMBLY 

CONNECT CHORD SWITCH TO CONTROL ASSEMBLY 

CONNECT KEYBOARD TO SOLO TUNER ASSEMBLY 

CONNECT ORGAN OSCILLATOR ASSEM.TO POWER F»^K 

CONNECT ORGAN OSCILLATOR AS5EM. TQ KEYBOARD 



DIAGRAM OF 
ORGANi 
»-4 (form B) 



51 



I 



3 



SPEAKER 
T^RECEPTACl 




reference: SrMSOLS FOR COMPONENTS REFER TO SCHEMATIC DIAGRAM FI&L 



FIGURE 13 



NSIDE OF GENERATOI 



RADIO- PHOMO INPUT IM CONSOLES 5ERIAL NO. 9337 AND ABOVE 

RADIO-PHONO INPUT IN CONSOLES BELOW SERIAL NO. 93i7 




REFERENCE 5YMB0L5 FOR COMPONENTS REFER TO SCHEMATIC DIAGRAM FiGUC 



FIGURE 13A- INSIDE OF GENERATOR 



^-0> 




"CHS^JTS REFER TO SCHEMATIC DIAGRAM FIGURE 6 



r 



INSIDE OF GENERATOR 



MODEL S - SERIAL NUMBERS BELOW 3500 




SPEAK 
R£C£P1 




REFERENCE SYMBOLS FOR COMPONENTS REFER TO SCHEMATIC DIAGR 



FIGURE I3B ~ INSIDE OF GENERATO 




REFEREMGE SYMBOLS FOR COMPONENTS REFER TO SCHEMATIC OiAGR^ 



FIGURE i5C- INSIDE OF 6ENERAT0I 




COMPONENTS REFER TO SCHEMATIC DIAGRAM "^l^^i^T^^ 

- INSIDE OF GENERATOR MODEL S-1 



■\ 



SOLO INPUT TRA HSF T1 



SERIAL NUMBER 12,000 AND ABOVE 




^NENTS REFER TO SCHEMATIC DIAGRAM FI6UR 

iNSlDE OF GENERATOR MODEL S-4 FORM 



55 




REFERENCE SYMBOLS FOR COMPONENTS REFER TO SCHEMATIC OlASajJ- 

FIGURE I3D- INSIDE OF GENERATDR 



S^ 





BK 


i3 >■ 




L6Z 




TYPE 6 







BK 


Z ^ 

^0 > 




L59 




TYPE 3 





L5d 
TYPEZ 



L57 
TYPE I 






Ht 


« 


CO 

u 


en 
O 




R co*^ponEnts refer to schematic diagram figure 6D 



VSQLO mPUT TRANSF. 1\ 

i- INSIDE OF GENERATOR MODEL S-4 FORMS 



SERIAL NUMBER 230OO AND ABOVE 



57 



-SOLO TIMBRES- 



-SOLO REGISTERS - 



SECOND VOICE FIRST VOICE FULL TONE D^fP TONE /^°^0^ FAsf ATTACK WOoSw^NDS ^^^^^^^ '^""^^ 



PILOT 
LAMP 



26A 27A 
BN BN 



•nF X^\\\\\\\\^|K\\\\\\\\\\VtR\\\\\\\\\\\^ - 



L38 
BRILLIANT 

COIL 



D a 

SOLO TIMBRE CIRCUITS 




BALANCERS 




FIGURE 14 - WIRING OF CONTROL ASS 

(REAR view) ^ 



1 



-SOLO TIMBRES- 



-SOLO REGISTERS - 



SECOND VOICE FIRST VOICE FULL TONE DEEP TONE /^^^O^ FAsfAT^TACK WOODWINDS ^°^«^^<^ ^^^^^^^ 



BASS ^O^' 




riK\\\\v\ 



PILOT 
LAMP 

o 



26A 27A 
BN BN 



n 



L39 




L40 


?ND 




fST 


VOICE 




VOICE 


INDUCTOR 




INDUCTOR 



D - 

SOLO TfMBRE CIRCUITS 





FIGURE 14A-WIRING OF CONTROL ASSEK 

(REAR view) 



•^f 



I 




STRINGS PEDAL 



- CHORDS - 

MUTE 




„,,,^ SUSTAIN VOLUME 

FAST DECAY ^^ '^ CANCEL SOFT 



note: lugs marked b are grounded by 
bare wire under panel. 



- WIRING OF CONTROL ASSEMBLY - MODEL S AND 5M 
(rear view) 




this condenser 
IM model s-1 only 



COLOR CODE 


BK 


BLACK 


BN 


BROWN 


R 


RED 


OR 


ORANGE 


YEL 


YELLOW 


GN 


GREEN 


BL 


BLUE 


GY 


GREY 


SH 


SHIELDED 



SEE FIGURE 7 FOR MEANING 
OF WIPE CODE LETTERS 



r 



O REGISTERS - 

TENOR 



VIBRATO CANCELS 

SOLO SOLO 

SMALL WIDE 



-ORGAN- 



ORSAN AND 
CHORDS 



PEDAL 
f^AST DECAY 



- CHORDS - 

MUTE 



SUSTAIN 
CANCEL 



VOLUME 
SOFT 




■IJ BK (form B OWLY) 

-note: LUGS MARKED B ARE GROUNDED BY 
BARE WIRE UNDER PANEL. 



^ING OF CONTROL ASSEMBLY - MODEL S-4 

(REAR view) 






COLOR CODE 


BK 


BLACK 


BN 


BROWN 


R 


RED 


OR 


ORANGE 


YEL 


YELLOW 


GN 


GREEN 


BL 


BLUE 


GY 


GREY 


SH 


SHIELDED 



SEE FIGURE 7 FOR MEANING 
OF WIRE CODE LETTERS 



59 



INDEX 



Accent - 




6,8 


Amplifier 




16 


Attack 




6,8,16 


Balancers 




B,9 


Rennoval 




34 


Bass rectifier 




11 


"Big Steps" tuning switch 




10 


Busbars and busbar shifters 


10, U, IV, 26 


Buttons (See Chord buttons) 






Chord division 




7 


Service suggestions 




30,31 


Chord bar 




7,8,14 


Removal 




35 


Chord buttons 




U 


Removal 




35 


Chord notes 




U,16 


Chord oscillator 




12, U 


Chord switch 




23 


Removal 




35 


Components list 




32,33 


Contacts 




10,14,16 


Cleaning 




26 


Control tablets (See Tablets) 






Control assembly 




23 


Control tubes 


11. 


12,14,16 


Earphones 




5 


Expression control 


^: 


9 ,17,23 


Extension speaker 




5 


Frequency dividers 




11,16 


Frequency range, solo oscillator 


10 


Frequency range, organ oscillato 


rs 12 


Frequency range, chord oscillato 


rs 12 


Frequency range, pedal divide 


rs 


16 


Generator assembly 




17 


Removal 




35,36 


Removal of coil 




36 


Installation 




5 


Keyboard 




10,17 


Removal 




37 


Removal of key 




36 


Limiter 




16 


Maintenance 




5 


Microphone input 




5 


Musical terms 




5 


Organ division 




7 


Service suggestions 




30 


Organ oscillators and oscillator 




assembly 




17 


Removal 




38 


Removal of coil 




38 


Oscillator rectifier 




10 


Oscillation, radio frequency 




28 


Parts list 




32,33 


Pedals 




16,23 


Removal 




38 


Pedal division 




7 


Service suggestions 




30,31 


Pedal switch 




23 


Removal 




38 


Phase inverter 




17 


Phonograph input 




5 



61 



Pilot light 


1 

7 
6 


Removal 


Playing instructions 


Power pack 


17,23 


Power switch (See Switch) 




Radio input 


5 


Register controls (See Tablets) 




Removal of parts for repair or 




replacement 


34,38 


Service suggestions 


26,31 


"Small Steps" tuning switch 


10 


"Solo" division 


7 


Service suggestions 


28,29 


Solo oscillator 


10 


Solo controls (See Tablets) 




Specific service suggestions 


28,31 


Stop tablets (See Tablets) 




Sustain 


6 


Switch, power (on-off) 


23 


Removal 


36 


Tablets 


8,26 


Bass 


8,11 


Brilliant 


9,11 


Deep Tone 


9,11 


First Voice 


9,11 


Flutes 


8,12 


Full Tone 


9,11 


Mute 


8,14 


Organ and Chords 


8,10,12 


Pedal Fast Decay 


8,16 


Second Voice 


9,11 


Solo Accent 


8,12 


Solo Fast Attack 


8,11 


Solo Small 


I 1 


Solo Wide 


Solo Woodwinds 


8,11 


Soprano 


3,11 


Strings 


8,12 


Sustain Cancel 


8,U 


Tenor 


8,11 


Volume Soft 


8,16 


Removal 


3A. 


Theory of operation 


9 


Timbre controls (See Tablets) 




Tone controls (See Tablets) 




Tone family selector 


8 


Tone generators 


9 


Tubes, testing and replacement 


26 


Tuning 


12,27,28 


Tuning coils 


10,12,23 


Removal 


36,38 


Tuning condensors 


12,23 


Tuner assennbly 


23 


Turning on and off 


7 


Vibrato 


6,8,10,12 


Service suggestions 


28 


Vibrato controls (See Tablets) 




Voltages 


28 


Volunne 


16 


Factory adjustment 


17 


Wave shapes 


28 







6^^ 



n6 



J^Y 



hi 












r 



Printed in U. S. A. 



I